WO2017180193A1

WO2017180193A1 - Internal unstacker for a heat treatment furnace

Info

Publication number: WO2017180193A1
Application number: PCT/US2016/064556
Authority: WO
Inventors: Paul M. Crafton; Shanker Subramaniam
Original assignee: Consolidated Engineering Company, Inc.
Priority date: 2016-04-11
Filing date: 2016-12-02
Publication date: 2017-10-19

Abstract

A system for applying a thermal treatment to metal components, such as castings or forgings, loaded within a stack of containers includes a heat treatment furnace having heating/soak zone(s), an unstacking zone, and an exit zone with an exit door at an end thereof. The furnace includes a first conveyor configured to carry the stack at a first speed through the heating/soak zone(s) and a second conveyor extending between the first conveyor and the exit zone that is configured to receive the stack at the first speed from the first conveyor. The furnace also includes a lifting apparatus within the unstacking zone that lifts one or more upper loaded containers in the stack off of one or more lower loaded containers, after which the second conveyor carries the lower loaded containers away from the unstacking zone toward the exit door at a second speed that is greater than the first speed.

Description

INTERNAL UNSTACKER FOR A HEAT TREATMENT FURNACE

CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority to U.S. Provisional Patent Application No.

62/320,760, filed April 11, 2016. The specification and drawings of this U.S. Provisional Application is by this reference incorporated herein in its entirety.

FIELD

[0002] The present invention relates generally to conveyance systems for moving trays or baskets loaded with metal components, such as castings or forgings, through a furnace during thermal treatments, such as a solution heat treatment and subsequent quench.

BACKGROUND

[0003] As with most manufacturing systems known in the industrial arts, it is often desired to increase the output of a particular thermal treatment system or process without sacrificing the quality of the resulting metal components, such as casting or forgings. Previous attempts to improve the throughput of a thermal treatment system have included increasing the size of the entry and exit openings/doors of the heat treatment furnace and expanding the size and capacity of the quenching station. This allows multiple trays or baskets loaded with components to be stacked on top of each other as they pass through the heat treatment and quenching portions of the manufacturing process, thereby increasing the number of components that can be thermally treated at the same time. This process typically involves stacking a number of loaded trays or open baskets, one on top the other, prior to entry into the furnace, withdrawing the stack at the furnace exit, and then quickly moving the entire stack, as a unit, into the quench zone where all of the components contained within the stacked baskets are quenched at the same time. The stack is moved into the quench zone as a unit because, as known to those of skill in the art, minimizing the lag time experienced by the components between withdrawal from the furnace and commencement of quenching can lead to better material properties.

[0004] The heating in the furnace of a casting located within a center portion of the stack to a target heat treatment temperature is generally not affected by the adjacent components and container structures, since the desired temperature change is gradual and continuous over a number of minutes. This is especially true for smaller components or components having simple shapes that allow for the ready circulation of hot air or gas between and around the baskets and components. It has been found, however, that the presence of many components in close vicinity to each other can adversely affect the quench stage, which is generally very rapid and occurs within seconds. In other words, the sheer quantity of components in a stack of loaded baskets can affect the quench of the components in different baskets or even those within the same basket, with those being closest to the source of quenching fluid(s) and being quenched first or with a faster quench rate generally having better material properties than those that are quenched later or with a slower quench rate. This reduction in quality of a portion of the components loaded within the stacked containers continues to be a deterrent to modifying casting manufacturing systems to accommodate stacked trays or baskets

[0005] Thus, a need exists for a system for applying a thermal treatment to metal components or parts that allows for the use of stacked trays or baskets with a furnace to increase the overall throughput of the manufacturing process, but still provides for the rapid and uniform quenching of each component loaded within the stacked containers to maintain the quality of the resulting components. It is toward such a thermal treatment system that the present disclosure is directed.

SUMMARY

[0006] Briefly described, one embodiment of the present disclosure comprises a system for applying a thermal treatment to metal components, such as castings or forgings, that are loaded within a stack of containers. The system includes a heat treatment furnace having a plurality of heating/soak zones, an unstacking zone, and an exit zone with an exit door at an end thereof. The furnace includes a first conveyor configured to carry the stack at a first speed through the heating/soak zones and a second conveyor extending between the first conveyor and the exit zone that is configured to receive the stack at the first speed from the first conveyor. The furnace also includes a lifting apparatus within the unstacking zone that lifts one or more upper loaded containers in the stack off of one or more lower loaded containers, after which the second conveyor carries the lower loaded containers away from the unstacking zone and toward the exit door at a second speed that is greater than the first speed. The thermal treatment system can also include a quench station that is located downstream of the exit door, and is configured to receive the lower loaded containers that have been separated from the stack and quench the components loaded therein.

[0007] Another embodiment of the disclosure includes a method for processing metal components within a thermal treatment system, in which the components are loaded within a plurality of containers that are stacked one on top of the another to form a stack of loaded containers. The method includes the steps of loading the stack of loaded containers into a heat treatment furnace that includes one or more heating/soak zones, an unstacking zone, and an exit zone having an exit door for the heat treatment furnace at an end thereof. The method also includes moving the stack downstream through the heating/soak zones and toward the unstacking zone on a first conveyor operating at a first speed, and upon reaching the unstacking zone, transferring the stack from the first conveyor to a second conveyor. The method further includes lifting, within the unstacking zone, one or more upper loaded containers in the stack off of one or more lower loaded containers, and then moving the lower loaded containers away from the unstacking zone and toward the exit door on the second conveyor that is now operating at a second speed that is greater than the first speed. The method can also include the steps of moving the lower loaded containers that have been separated from the stack from the exit door into a quench station located downstream of the exit zone, followed by operating the quench station to quench the components loaded within the lower loaded containers.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 is a schematic side view of a thermal treatment system having a casting container unstacking system located internal to the furnace, in accordance with a representative embodiment of the present disclosure.

[0009] FIG. 2 is another schematic side view of a thermal treatment system having a casting container unstacking system located internal to the furnace, in accordance with another representative embodiment of the present disclosure.

[0010] Those skilled in the art will appreciate and understand that, according to common practice, the features of the drawings discussed below are not necessarily drawn to scale, and that dimensions of various features and elements of the drawings may be expanded or reduced to more clearly illustrate the embodiments of the present disclosure described herein.

DETAILED DESCRIPTION

[0011] The following description is provided as an enabling teaching of exemplary embodiments of a thermal treatment system and method that provides for the unstacking of trays or baskets loaded with metal components, internally within a heat treatment furnace, so that the number of loaded baskets exiting the furnace and entering a quench system at one time can be reduced. As described below, the internal unstacking system or lifting apparatus and method can provide several significant advantages and benefits over thermal treatment systems in which stacked trays or baskets of components or parts exit the furnace and enter the quenching zone at the same time. The recited advantages are not meant to be limiting in any way, however, as one skilled in the art will appreciate that other advantages may also be realized upon practicing the present disclosure.

[0012] Furthermore, a skilled artisan will also recognize that changes can be made to the embodiments described while still obtaining the beneficial results. It will also be apparent that the desired benefits of the embodiments described can be obtained by selecting some of the features of the embodiments without utilizing other features. In other words, features from one embodiment or aspect may be combined with features from other embodiments or aspects in any appropriate combination. For example, any individual or collective features of method aspects or embodiments may be applied to apparatus, product or component aspects, or embodiments and vice versa. Those who work in the art will further recognize that many modifications and adaptations to the embodiments described are possible and may even be desirable in certain circumstances, and are a part of the invention. Thus, the following detailed description is provided as an illustration of the principles of the embodiments and not in limitation thereof, since the scope of the invention is to be defined by the claims.

[0013] Referring now in more detail to the drawing figures, wherein like parts are identified with like reference numerals throughout the several views, FIG. 1 illustrates one embodiment of the thermal treatment system 10 that generally includes a heat treatment furnace 20 with a downstream portion 24 having one or more heating/soak zones 30, an unstacking zone 40, and an exit zone 50. The thermal treatment system 10 can also include a quench station 80 located downstream of the exit zone 50. Although not shown, the upstream portion of the furnace 20 includes an inlet door having an opening height that is sufficient to allow stacks 91 of containers 90, such as trays or open baskets, to be carried into the furnace enclosure 22 on a first conveyor 60. Each of the individual containers 90 is loaded with metal components or parts, such as castings or forgings, that will undergo the thermal treatment process applied by the system 10.

[0014] After entering the furnace 20, the stacks 91 of loaded containers 90 are conveyed downstream through a plurality of heating/soak zones by the first conveyor 60 that can be driven by one or more single -drive motors at a substantially constant first speed. Both the heating rate provided by the heating/soak zones and the first speed are generally selected to ensure that all of the components or parts within the containers 90 reach a desired heat treatment temperature by the time the stacks 91 pass through the last heating/soak zone 30 and enter the unstacking zone 40. For instance, the last heating/soak zone 30 can include a fan 32 and an optional burner 34 to aid in the application of heat to the stack 91 of loaded containers 90 to finish raising the components therein to the target temperature. In one aspect the unstacking zone can also include an optional fan 42 and/or burner 44 that can help maintain the temperature of the components being processed during the time they are located within the unstacking zone. As depicted in the drawing, the first conveyor 60 can be a typical roller conveyance system known for application in roller hearth furnaces. Nevertheless, in other embodiments the conveyor can be a chain, walking beam, or any other type of conveyance system known to one of skill in the art for application in a heat treatment furnace 20.

[0015] During movement from the last heating/soak zone 30 into unstacking zone 40, the stacks 91 of loaded containers 90 can be transferred from the first conveyor 60 moving at the first speed to a second, generally similar conveyor 64 that is temporarily moving at the same first speed, but which is also capable of moving at one or more different speeds. For instance, the second conveyor 64 can be driven by one or more dual-drive or variable frequency drive (VFD) motors, and in some embodiments can include a clutch mechanism to smooth the transition between speeds. For the thermal treatment system 10 of FIG. 1, the second conveyor 64 in the unstacking zone 40 can extend between the first conveyor 60 located in the soak zone 30 and a third conveyor 68 located in the exit zone 50, with the third conveyor 68 being driven by one or more motors at a second speed that is greater than the first speed. In other embodiments (not shown) the second conveyor can extend through both the unstacking zone 40 and the exit zone 50 clear through to the exit door 54.

[0016] Included within the unstacking zone 40 is an unstacking system 70 or lifting apparatus

72 that is adapted to separate the containers 90 in the stack 91 by picking up one or more upper loaded containers 92 while leaving one or more lower loaded containers 94 resting on the second conveyor 64. In one aspect the lifting apparatus 72 can be a robotic manipulator or similar device having jaw arms 74 with attachment ends 76 that are configured to engage with corresponding attachment features formed into the containers 90. However, other types of mechanical unstacking apparatuses suitable for operation within the hot environment is maintained within the furnace enclosure 22 are also possible and considered to fall within the scope of the present disclosure.

[0017] As shown in FIG. 1, the jaw arms 74 of the manipulator 72 can engage with and lift the second lowest container 93, and any additional upper loaded containers 92 resting atop the second lowest container 93, up and away from the second conveyor 64. Only a single lower loaded container 94 then remains on the second conveyor 84 to be carried downstream toward the exit zone 50. At this point the speed of the second conveyor 64 can be increased to the higher speed of the third conveyor 68 so as to quickly move the lower loaded container 94 out from under the remaining containers in the stack, onto the third conveyor 68 in the exit zone 50, and finally out of the furnace 20 through the exit opening 52. In one aspect the speed of the second conveyor 64 can be reduced or stopped once the lower loaded container 94 is transferred to the third conveyor 68. After a time interval used to establish a desired spacing between quench cycles, the lifting apparatus 72 can be operated to lower the upper loaded containers 92 down onto the second conveyor, disengage from the lowest container, re-engage with the new second lowest container 93, and then again lift the upper loaded containers 92 away from the second conveyor 64 to allow another single lower loaded container 94 to be carried downstream and out the exit door 54. In this way the stacks 91 of loaded containers 90 can be sequentially unstacked, from the bottom up, into individual loaded containers 94 that pass through the exit opening 52, one at a time, to leave the furnace 20 and enter the quench zone 80.

[0018] Once the last loaded container 94 in the stack of loaded containers has been released onto the third conveyor 68 for transport to the exit, the speed of the second conveyor 64 can be reset to the first speed that matches the speed of the first conveyor 92, and the lifting apparatus 70 can be reset to engage with the second lowest container 93 in the next stack 91 of loaded containers 90 as it is rolled or conveyed from the last heating/soak zone 30.

[0019] While the lifting apparatus 72 or robotic manipulator is shown in FIG. 1 as engaging with the second lowest container 93 in the stack 91, so that only a single lower loaded container 94 is separated from the stack at one time, it will be appreciated that the unstacking system 70 is not limited to this procedure and that other unstacking operations are also possible. For instance, in some embodiments lifting apparatus 72 could alternatively engage with the third or forth lowest container in the stack 91 so that a shorter stack of loaded containers, instead of a single container, is carried downstream on the second conveyor 64 toward the exit zone 50.

[0020] The stacks 91 of loaded containers 90 can be separated into individual loaded containers 94 or smaller stacks or groups of loaded containers prior to exiting the furnace 20, as shown in FIG. 1 , so that the separated containers can be moved directly and swiftly from the exit opening 52 into the quench zone 80 for a rapid and uniform quenching of the limited number of castings or forgings contained therein. For the total immersion quenching system 82 shown in FIG. 1 , for instance, the single loaded container 96 within the quench zone 80 can be placed in a dipping apparatus 84 that quickly lowers the container into a quench tank 86 filled with a quench liquid 88, such was water, glycol, or oil. Upon immersion within the quench liquid 88 the components or parts loaded within the container 96 are rapidly cooled from a temperature very near the target heat treatment temperature inside the furnace enclosure 22 to a desired quench temperature in a matter of seconds, often within 10 to 20 seconds for the immersion quench. [0021] It will be appreciated that other forms of quenching and types of quench systems can also be incorporated into the thermal treatment system, such as a forced air quench (whether bulk air or directed air), a liquid spray quench (again with water, glycol, or oil), or combinations thereof, and may be considered to fall within the scope of the present disclosure. However, it may take longer, often up to 90, 120, or even 180 seconds, for the hot components to be cooled to the desired quench temperature using these other forms of quenching.

[0022] Once the temperatures of the metal components within the container are reduced to the desired quench temperature, the container 98 loaded with the quenched components can be removed from the quench tank and placed on an outlet rack 16 where it is available for re- stacking and/or removal to a remote location (e.g. an aging zone or oven, not shown) for natural or artificial aging of the components contained therein. In one aspect the components loaded within the single container 98 can be examined using automatic optical, infrared, or x- ray scanning systems, and the like, prior to combining the loaded container 98 into another stack for transfer to the aging zone.

[0023] Separating the stacks of loaded containers into single loaded containers 94 or smaller stacks of loaded containers prior to exiting the furnace can be advantageous by allowing the number of components that can be treated within a heat treatment furnace to be increased, while at the same time maintaining or even reducing the size of the quench system to one that only needs to accommodate a single or a limited number of loaded containers at one time. In addition to the reduced up front construction and ongoing operational costs of a smaller quench system, limiting the size of the quench system can perhaps more importantly provide for better control and application of the quench fluids to each group of components. It will be appreciated that the thermal treatment system of the present disclosure can therefore provide for higher capacity heat treatment systems while ensuring that the components loaded within a particular stack of containers consistently achieve material properties that are both high quality and more uniform across the batch.

[0024] In addition, separating the stacks of loaded containers into single loaded containers 94 or smaller stacks of loaded containers prior to exiting the furnace can also be advantageous by reducing the profile of the exit zone 50 as well as size of the exit opening 52 and/or the exit door 54. This can limit the opportunity for cooler, ambient air to enter in and mix with the heated air within the enclosure with possible detrimental temperature affects to the components being treated within the furnace. This can also minimize the amount of heated air that exits the system as wasted energy with the outward passage of each loaded container 94 through the exit opening 52. For example, as one of the principle operating costs for the heat treatment furnace can be the generation of the heat necessary to raise and maintain the temperature of the components being treated, any improvement in efficiency due to reductions in heat loss or the inadvertent ingress of cooler ambient air can result in significant cost savings.

[0025] In another aspect of the thermal treatment system 10 also shown in FIG. 1, the primary exhaust outlet 58 for the heat treatment furnace 20 can be moved to the exit zone 50 and provided with an internal damper 56 or similar device that can partially or completely close the exhaust outlet in sequence with the opening of the exit door 54. In this way the exit zone 50 of the furnace 20 can become slightly pressurized with the opening of the exit door 54, so that the hot exhaust air flows continuously out of the exit opening 52 and the cooler ambient air is prevented from entering. It will be appreciated that such an exhaust outlet configuration would not likely be as effective at minimizing heat loss or restricting the ingress of cooler ambient air if the exit opening 52 and exit door 54 where enlarged so as to allow for the exit passage of a complete stack 91 of loaded containers 90.

[0026] FIG. 2 depicts another embodiment of the thermal treatment system 110 that is adapted for use with a variety of differently-sized containers that can be loaded with a variety of differently-sized and shaped components. The thermal treatment system 110 can include a programmable control system (not shown) and a heat treatment furnace 120 having an adjustable unstacking system 170 or lifting apparatus 172 and an adjustable exit door 154. The control system can be provided with sensors or monitors that detect the size and number of the loaded containers 190, 192, 194 that make up the different stacks 191 , 193 as they are carried through the plurality of heating/soak zones by the first conveyor 160. When a stack

193 made up of oversize or larger containers 192, 194 reaches the unstacking zone 140, for example, the control system can direct the lifting apparatus 172 to separate the containers 192,

194 by engaging and picking up the upper loaded container 192 while leaving the lower loaded container 194 resting on the second conveyor 164.

[0027] The lower loaded container 194 can then be carried into the exit zone 150 that is sized to receive both the larger, oversized containers 194 as well as the smaller, standard containers 190 that make up stacks 191 that can also be processed by the thermal treatment system. The exit zone 150 and exit opening 152 can also be sized to allow the passage of the differently sized containers 190, 194, and the exit door 154 can be directed by the control system to open only as far as needed to allow a single loaded container 194 or a reduced number of containers to exit the furnace 120 at one time, with the height of the opening being adjustable according to the size of the loaded container 194. [0028] Although not shown in the drawings, it will be appreciated that containers of different size can be stacked together to form a single stack, with the programmable control system being able to identify the type and quantity of the containers within each stack being loaded in the heat treatment system. The control system can then automatically adjust the lifting apparatus 172 and exit door 154 to unstack the loaded containers 192, 194 in the correct configuration to allow the loaded containers to pass through the exit opening 152 one at a time, and in a desired order. This capability for co-mingling different types of components or parts in different sizes and combinations of containers can be further advantageous by allowing manufactures to utilize a single thermal treatment system for processing various types and sizes of components at the same time or even within the same stack, while avoiding time-consuming reconfiguration and/or modifications that would otherwise be necessary to separately process each type of casting.

[0029] The quench zone 180 of the thermal treatment system 110 can also be directed by the control system and adapted for use with the differently-sized containers. In the illustrated embodiment the quench zone 180 can include an adjustable and programmable quenching system 182 having one or more downwardly-directed air fans 184 for applying a bulk air quench, and/or a plurality of spray nozzles (not shown) that direct streams or mists of cooling liquid onto the components loaded into the container 196 that is positioned within the quench chamber 188. Furthermore, in addition to moving and positioning the differently-sized containers within quench chamber 188, in other aspects the control system can also adjust the activation, position, and/or orientation of the air fans and/or spray nozzles within a forced air/liquid spray quenching system 182 to customize the application of quenching fluids to the components.

[0030] As with the previous embodiment, once the components within the container reach the desired quench temperature, the container 198 loaded with the quenched components can be removed from the quench tank and placed on an outlet rack 116 where it is available for inspection, re-stacking, and/or removal to a remote location for natural or artificial aging of the components contained therein.

[0031] The invention has been described herein in terms of preferred embodiments and methodologies considered by the inventor to represent the best mode of carrying out the invention. It will be understood by the skilled artisan, however, that a wide range of additions, deletions, and modifications, both subtle and gross, may be made to the illustrated and exemplary embodiments without departing from the spirit and scope of the invention. These and other revisions might be made by those of skill in the art without departing from the spirit and scope of the invention that is constrained only by the following claims.

Claims

1. A system for processing metal components loaded within a plurality of containers, the containers being stacked one on top of another to form a stack of loaded containers, the system comprising:

an unstacking zone;

a first conveyor configured to carry a stack of loaded containers;

a second conveyor configured to receive a stack of loaded containers from the first

conveyor; and

a lifting apparatus within the unstacking zone and configured to lift an at least one upper container of a stack of loaded containers off of an at least one lower container of a stack of loaded containers.

2. The system of claim 1, further comprising:

a heat treatment furnace including:

at least one heating/soak zone;

the unstacking zone; and

an exit zone having an exit door for the heat treatment furnace at an end

thereof; wherein

the first conveyor is configured to carry a stack of loaded containers at a first speed through the at least one heating/soak zone;

the second conveyor extends between the first conveyor and the exit zone and is configured to receive a stack of loaded containers at the first speed from the first conveyor; and

wherein the second conveyor is configured to carry an at least one lower container of a stack of loaded containers away from the unstacking zone toward the exit door at a second speed greater than the first speed.

3. The system of claim 2, further comprising a quench station located downstream of the exit zone and configured to receive an at least one loaded container separated from a stack of loaded containers and to quench the components loaded therein.

4. A system for applying a thermal treatment to metal components loaded within a plurality of containers stacked one on top of another to form a stack of loaded containers, the system comprising: a heat treatment furnace including:

at least one heating/soak zone;

an unstacking zone; and

an exit zone having an exit door for the heat treatment furnace at an end

thereof;

a first conveyor configured to carry the stack of loaded containers at a first speed through the at least one heating/soak zone;

a second conveyor extending between the first conveyor and the exit zone and

configured to receive the stack at the first speed from the first conveyor; and a lifting apparatus within the unstacking zone and configured to lift at least one upper loaded container in the stack off of at least one lower loaded container, wherein the second conveyor is configured to carry the at least one lower loaded

container away from the unstacking zone toward the exit door at a second speed greater than the first speed.

5. A method for processing metal components loaded within a plurality of containers stacked one on top of another to form a stack of loaded containers, the method comprising:

moving the stack on a first conveyor, transferring the stack from the first conveyor to a second conveyor;

within the unstacking zone, lifting an at least one upper container in the stack off of an at least one lower container; and

moving the at least one lower container.

6. The method of claim 5, further comprising:

loading the stack of loaded containers into a heat treatment furnace including at least one heating/soak zone, the unstacking zone, and an exit zone having an exit door to the heat treatment furnace at an end thereof;

moving the stack downstream through the at least one soak zone and toward the

unstacking zone on the first conveyor operating at a first speed; transferring the stack from the first conveyor to the second conveyor upon the stack reaching the unstacking zone; and

moving the at least one lower loaded container away from the unstacking zone toward the exit door on the second conveyor operating at a second speed that is greater than the first speed.

7. The method of claim 5, further comprising:

moving the at least one lower loaded container from the exit door into a quench station located downstream of the exit zone; and

quenching the components loaded within the at least one lower loaded container.

8. A method for processing metal components loaded within a plurality of containers stacked one on top of another to form a stack of loaded containers within a thermal treatment system, the method comprising:

loading the stack of loaded containers into a heat treatment furnace including at least one heating/soak zone, an unstacking zone, and an exit zone having an exit door to the heat treatment furnace at an end thereof;

moving the stack downstream through the at least one soak zone and toward the

unstacking zone on a first conveyor operating at a first speed; upon the stack reaching the unstacking zone, transferring the stack from the first conveyor to a second conveyor;

within the unstacking zone, lifting at least one upper loaded container in the stack off of at least one lower loaded container; and

moving the at least one lower loaded container away from the unstacking zone and toward the exit door on the second conveyor operating at a second speed that is greater than the first speed.