Hot stamping system and method.

CROSS REFERENCE TO THE RELATED APPLICATION

This North American Patent Application claims the benefit of the Provisional Patent Application

North American Serial Number 61 / 730,667 filed November 28, 2012, entitled Hot Stamping System And Method, the entire disclosure of the application is considered part of the disclosure of this application and is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of Invention

The inventions generally relate to a system and method for hot forming a plurality of parts, such as steel parts for automotive body and chassis applications.

two. Related art

Hot forming processes typically comprise heating a steel preform in a furnace, followed by stamping the heated preform between a pair of dies to form a shaped part, and quenching the shaped part between the dies. The steel preform is typically heated in the furnace to achieve an austenitic microstructure, and subsequently quenched in the dies to transform the austenitic microstructure to a

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martensitic microstructure. The process of^NIT^ 3Jl £ o rmacp hot preferably operates continuously to produce a plurality of shaped parts at a high rate and low cost. However, when the furnace malfunctions, the entire system must be shut down for a period of time while the furnace is being repaired, which increases the cost per part produced by the system.

BRIEF DESCRIPTION OF THE INVENTION

The invention provides a system for hot forming a plurality of parts, such as steel parts for use as automobile body or chassis components. The system comprises an oven that includes a plurality of shelves stacked vertically with respect to one another. Each shelf includes a plurality of rollers driven to transport a plurality of preforms through the oven. The oven also includes a plurality of heaters for heating the preforms, each heater being arranged adjacent to one of the shelves. Each shelf and the adjacent heater are removable from the oven, for example when the heater malfunctions. The system further includes a hot forming apparatus for shaping the heated preforms, and a preform feeder for conveying the heated preforms from the oven racks to the hot forming apparatus.

The invention also provides an Insl hot forming of a plurality of ^^^^ testsT method includes conveying a plurality 'dé' ..... pTé'f ófffláá 3 Tó ”along a plurality of shelves of an oven, and heating the plurality of preforms using a heater arranged adjacent to each shelf. The method also includes removing the heater and adjacent shelf from the oven when the heater malfunctions while continuing to heat the preforms on the other shelves. The method further includes transporting the heated preforms from the oven to a hot forming apparatus, and shaping the heated preforms in the hot forming apparatus.

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BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages of the present invention will be readily appreciated, as it is better understood by reference to the following detailed description when considered in connection with the accompanying drawings where:

Figure 1 is a side view of an exemplary hot forming system for producing a plurality of shaped parts; Y

Figure 2 is an exemplary die of a hot forming apparatus used in the system of Figure

1.

DESCRIPTION OF THE ABLE MODALITY:

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With reference to the Figures, where number ^ '^^' imi 'indicate parts 20 corresponding to the 1st Fefó^rraCt5 ”'1 a * S^m,Various views, an exemplary system 22 for hot forming a plurality of shaped parts 20 is shown generally in Figure 1. System 22 includes an oven 24 for heating a plurality of preforms 26, a forming apparatus 30 hot to shape heated preforms 26, and a preform feeder 28 to convey heated preforms 26 from oven 24 to hot forming apparatus 30. System 22 provides reduced downtime and thus reduced overhead costs per part 20, compared to other hot forming systems. System 22 also requires less floor space compared to the other systems.

The preforms 26 used to make the shaped parts 20 are typically formed of metal, but can be formed of other materials. In an exemplary embodiment, the preforms 26 are formed of steel material, such as pure steel or a steel alloy. Although the shaped parts 20 are typically designed for use as automotive body or chassis components, the parts 20 may alternatively be used in other applications.

System 22 includes oven 24 for heating a plurality of preforms 26 prior to

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Preforms 26 in oven forming apparatus 30 include a plurality of strips vertically relative to each other and a heater 34 disposed adjacent to each shelf 32. Each heater 34 may comprise a single heating element or a plurality of heating elements. of heating elements. For example, each heater 34 could include a plurality of tubes containing flue gas, or a plurality of heated coils. Each shelf 32 extends horizontally from a first side to a second side opposite the first side and has an area capable of supporting at least one preform 26, but preferably a plurality of preforms 26. In addition, each shelf 32 can be attached to others. shelves 32, and each shelf 32 and adjacent heater 34 are individually removable from oven 24.

Preferably, the oven 24 includes a plurality of chambers 36 stacked vertically with respect to one another and each including one of the shelves 32 and one of the heaters 34, as shown in Figure 1. Each chamber 36 is fixable individually to other cameras 36 and is individually removable from the stack of cameras 36. In the exemplary embodiment, a first door 38 is located on the first side of each chamber 36 and a second door 40 is located on the second side of each chamber 36 to seal the

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The first doors 38 can open automatically to receive unheated preforms 26, and the second doors 40 can automatically open to release the heated preforms 26 for subsequent shaping in the hot forming apparatus 30.

<td colspan="5">Shelves 32 of oven 24 include a plurality of</td>

<td>first</td><td>rollers 42</td><td>triggered</td><td>that extend from</td><td>the</td>

<td>first</td><td>side up</td><td>the second</td><td>side to transport</td><td>the</td>

preforms 26 through furnace 24. The first driven rollers 42 may comprise mechanically driven ceramic rollers or rollers of the type used in hearth type furnaces. The first driven rollers 42 of oven 24 can rotate continuously, remain stationary for periods of time, or oscillate back and forth, depending on the amount of heating desired. In addition, the first driven rollers 42 of one shelf 32 can move or rotate at a different rate than the first driven rollers 42 of another shelf 32. For example, the blanks 26 that are transported along one of the lower shelves 32 can remain in the oven 24 for a longer period of time than the preforms 26 that are transported along one of the upper shelves 32, to achieve different microstructures in those preforms 26.

As mentioned above, oven 24 includes the

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plurality of heaters 34 for heating ^{r L} DB bCP &amp; e? I? .DAD

INDUSTRIAL

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IIS3 as they move continuously through oven 24 or rest in oven 24 for a period of time. Each heater 34 is arranged adjacent to one of the shelves 32 to heat the preforms 26 arranged on that shelf 32. In the exemplary embodiment of Figure 1, each sealed chamber 36 includes its own heater 34. The heater 34 may comprise a burner of gas, an electric heater, or another type of heater. Heaters 34 preferably maintain all chambers 36 at approximately the same temperature, but could be configured to maintain one or more of chambers 36 at a different temperature from the other chambers 36. The temperature of chambers 36 can be adjusted to achieve desired microstructure in the preforms 26 moving through the chambers 36. For example, if the preforms 26 are formed of steel material, preferably the temperature of

Furnace 24 heat to austenitizing before being shaped.

typically includes a controller (not shown) to determine if preforms 26 have reached a predetermined temperature, either with detectors placed within chambers 36 or by monitoring the amount of time each preform 26 remains within oven 24, and to adjust the amount of time preforms 26 are in oven 24.

The furnace 24 of the inventive system is advantageous in

ΙΜ ^ Ϊ comparison with the ovens of other systems "^jof with * · nt · »-λ · νι.-ΛΓΕΑ η ·

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hot because it can continue to operate even if one or more of the heaters 34 malfunctions or fails. In this manner, the hot forming system 22 can continuously form the shaped parts 20 with little or no downtime. For example, the chamber 36 containing the malfunctioning heater 34 can be removed from the stack of chambers 36 and repaired while the preforms 2 6 continue to move through the other heated chambers 36. Alternatively, if oven 24 contains stack of shelves 32, malfunctioning heater 34 and the adjacent shelf can be removed from the stack. The reduction in downtime provided by system 22 reduces overhead fixed costs per formed part 20 produced. Furthermore, oven 24 with stacked chambers 36 or shelves 32 requires less floor space than other comparatively sized ovens.

The exemplary system 22 also includes a preform loader 48, preferably an indexing preform loader that includes a plurality of second driven rollers 44 to feed unheated preforms 26 to racks 32 of oven 24. Second driven loader rollers 44 48 of preforms are aligned with and timed to move with the first driven rollers 42 of one of the racks 32. In this way, the first and second ones rotate accordingly

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rollers 42, 44 driven

<td>rate and</td><td colspan="2">move one o</td><td>more of</td><td>the preforms</td><td> 26</td><td>not</td><td>heated</td><td>to</td>

<td>through</td><td>of the</td><td>first</td><td>door</td><td>38 and through</td><td>from</td><td>the</td><td>camera 36.</td><td>The</td>

<td>system</td><td> 22</td><td>also</td><td>can</td><td>include a</td><td colspan="2">robot</td><td>50 with</td><td>a</td>

<td colspan="2">controller</td><td colspan="3">to automatically arrange</td><td>the</td><td colspan="2">preforms 26</td><td>not</td>

heated in preform loader 48. Alternatively, the system 22 could be fed from a spool of material that is divided to form the plurality of preforms 26 at some point during the process.

In the exemplary system, the preform loader 48 can be moved vertically along the first sides of the chambers 36 to feed the preforms 26 onto each of the shelves 32 of the oven 24. This preform loader 48 is configured to lift or automatically lower the preforms 26 and feed them into the open chambers 36. Figure 1 shows the preform loader 48 in a lower position, an intermediate position, and an upper position. Alternatively, preform loader 48 could be removable from oven 24 and mounted on another robot (not shown). The second robot could insert the preform loader 48 into the oven 24 after the first robot 50 places the unheated preforms 26 in the preform loader 48. In still another embodiment, the unheated preforms 26 could be loaded into the furnace 24 manually or by another type of mechanical preform loading system.

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System 22 also includes hot forming to form heated pre-urines 2 6 into a plurality of shaped portions 20. The hot forming apparatus 30 is preferably a hot stamping press that includes an upper die 52 and a lower die 54 facing each other and having at least one cavity 56 therebetween to shape at least one of the heated preforms 26. In the exemplary embodiment, the dies have a plurality of cavities 56 for simultaneously forming at least one of the heated preforms 26 in a plurality of shaped parts 20, or a plurality of heated preforms 26 in a plurality of shaped parts 20. The cavities 56 could be similarly molded or could be molded differently to simultaneously produce different types of parts 20. Furthermore, the upper die 52 and the lower die 54 are interchangeable and removable from the hot forming apparatus 30. For example, upper die 52 and lower die 54 can be interchanged for dies having different designs. Figure 2 illustrates an exemplary die 52, 54 that includes a three-by-five arrangement of cavities 56 for simultaneously producing five parts 20 of three different automotive components. However, any desirable number of cavities 56 could be included in the hot forming apparatus 30. The esaatasatiAsasaasa &amp; ssizct

ΙΜΡΪ® hot forming apparatus 30 with cavities 56 provides a batch forming process that enables savings in manufacturing costs by reducing the amount of time required to produce each part 20.

The hot forming apparatus 30 also includes a plurality of cooling ports 58 that extend along the cavities 56 to transport a cooling fluid therethrough, such as water or some other cooling fluid. In this way, the shaped parts 20 can be turned off after the forming process is completed, and while the shaped parts 20 are still in the cavities 56. The amount and temperature of the water fed through the cooling ports 58, as well as the shapes and locations of the cooling ports 58, can be chosen to achieve a desired quench rate, thus achieving the desired microstructure in the metal parts 20. For example, when the preforms 26 are formed from the steel material, the quenching step includes rapidly cooling the shaped parts 20 to transform the austenitic microstructure to a martensitic microstructure. Furthermore, one or more of the cooling factors could be varied for different cavities 56 to simultaneously produce a plurality of shaped parts 20 having different microstructures.

1NS .;

The hot forming apparatus 30 typically a controller (not shown) for actuating the dies 52, 54 after one or more heated preforms 26 are properly positioned between the dies 52, 54. The hot forming apparatus controller 30 also You can adjust the amount of time that the parts 20 are turned off between the matrices 52, 54.

Exemplary system 22 also includes preform feeder 28 disposed opposite preform loader 48 and continuously extending from oven 24 to hot forming apparatus 30 to convey heated preforms 26 to hot forming apparatus 30. The preform feeder 28 is preferably an indexing preform feeder and includes a plurality of third driven rollers 46. The indexing feature of the preform feeder 28 may comprise a plurality of indexing fingers to align the heated preforms 26 in a predetermined position prior to entering the hot forming apparatus 30. The preforms 26 are preferably positioned as close to each other as possible to reduce waste material during the hot forming step. The exemplary embodiment preform feeder 28 is vertically movable along the second sides of the shelves 32 to transport the

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<img file="MX341019B_D0011.tif" />

preforms 26 heated from each of "fosAl to hot forming apparatus 30. The third driven rollers 46 are aligned with and clocked to move with the first driven rollers 42 of the shelves 32 at approximately the same rate. Alternatively, the preform feeder 28 could be removable, and another robot (not shown) could introduce the preform feeder 28 into the oven 24. The preform feeder 28 is preferably isolated from the surrounding environment, or includes a heater (not shown) so that the heated preforms 26 are at a desired temperature when they enter the hot forming apparatus 30. The system 22 may also include another robot (not shown) to lift the heated preforms 26 out of the preform feeder 28 and place the heated preforms 26 in position relative to the cavities 56 of the hot forming apparatus 30. Alternatively, system 22 could include another method, such as a mechanical transfer system, for conveying heated preforms 26 from oven 24 to hot forming apparatus 30.

System 22 typically also includes transfer bars (not shown) for removing shaped portions 20 from hot forming apparatus 30 and depositing them on a conveyor 60. Conveyor 60 is disposed adjacent to hot forming apparatus 30

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INSTO '.' 'Τ opposite the preform feeder 28 for conveying * the shaped parts 20 away from the hot forming apparatus 3Ü 3e * ”. Alternatively, the shaped parts 20 could be removed from the hot forming apparatus 30 through another automated or manual process.

Exemplary system 22 also comprises a system controller 62 that includes a computer, as shown in Figure 1, for controlling preform feeder 28, preform loader 48, and conveyor 60. For example, system controller 62 may instruct preform loader 48 to move vertically along the first side of oven 24 to feed unheated preforms 26 into open chambers 36 of oven 24 and may instruct feeder 28 of preforms to move vertically along the second side of oven 24 to transport heated preforms 26 away from particular chambers 36 once they reach a predetermined temperature. Additionally, system controller 62 may instruct preform loader 48 to automatically bypass any chambers 36 in oven 24 that are malfunctioning or have already been removed. This allows the system 22 to continue to operate even if one or more heaters in the furnace 24 malfunction, which is in contrast to other known hot stamping systems that must shut down completely if the heater malfunctions. As discussed above, the robot 50 the horn

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The hot-forming system is controlled by its own controllers, ^ --ir, ^ ppnrH, ^ η-t-Amente, but the system controller 62 can share signals between the controllers of the robot 50, the oven 24, and the apparatus 30 hot forming. The system controller 62 also verifies that each component of the system 22 is operating correctly in order to maximize efficiency.

The invention also provides a method for hot stamping a plurality of steel parts 20 that provides reduced overhead costs per part 20 and that requires less floor space compared to other hot forming methods. The first method includes feeding the preforms 26 onto the racks 32 of the oven 24, typically moving the unheated preforms 26 along the second driven rollers 44 of the preform loader 48, through the first doors 38 of the chambers 36, and on the shelves 32. The second driven rollers 44 align with the first driven rollers 42 of one of the shelves 32, and the first and second driven rollers 42, 44 are timed to move together at approximately the same rate. The method also includes moving the preform loader 48 vertically relative to the first sides of the shelves 32 and feeding the unheated preforms 26.

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about each could include 32 shelves. Altern ^ E ^ i / amente /:

insert preform loader 48 into oven 24.

The method subsequently includes heating the preforms 26 while the preforms 26 are arranged on the racks 32, and transporting the preforms 26 along the first driven rollers 42 through the oven 24. The metal preforms 26 remain in the oven 24 during an amount of time capable of providing a desired microstructure. For example, the preforms 26 can be heated while continuously moving through the oven 24, or while resting on the shelves 32 while the first driven rollers 42 remain stationary for a period of time. In another embodiment, the first driven rollers 42 oscillate back and forth with the preforms 26. The first oscillating driven rollers 42 can prevent hot and cold spots along the preforms 26, can prevent the preforms 26 from sagging, and can help maintain the integrity of any coating applied to the preforms 26.

If one of the malfunctioning heaters 34, the method includes removing the chamber 36 containing the malfunctioning heater 34, or removing the malfunctioning heater 34 and adjacent shelf 32, while continuing to heat the preforms 26 arranged in the others. shelves 32. The method • ύ

1 'A / ϊ Ρ Τ © Ε ΙΑ ifebrtf.'feJt¹· ÍKí ^ LfilI ^ uAÍL *** while continuing to heat and transport the preforms 26 along the other shelves 32 of the oven 24. Additionally, the method may include skirting one of the shelves 32 of the oven 24 when the adjacent heater 34 the shelf 32 malfunctions, or skirting one of the chambers 36 when the heater 34 contained in the chamber 36 malfunctions. In this way, the method can continue to manufacture the shaped parts 20 even when one of the furnace heaters 24 is ruined.

The method subsequently includes transporting the heated preforms 26 from the shelves 32 of the oven 24 to the hot forming apparatus 30. The conveying step includes moving the heated preforms 26 from the first driven rollers 42 of the oven 24 toward the third driven rollers 46 of the preform feeder 28. The third driven rollers 46 align with the first driven rollers 42 and are timed to move in conjunction with the first driven rollers 42. In the exemplary embodiment, the method includes moving the preform feeder 28 vertically along the stack of shelves 32 and transporting the heated preforms 26 from each of the shelves 32 to the hot forming apparatus 30. In one embodiment, the method includes isolating the heated preforms 26 from the outside environment to

They are transported from furnace 24 to hot forming apparatus, or heating preforms 26 as they are conveyed from furnace 24 to hot forming apparatus 30.

Once the heated preforms 26 are disposed between the dies 52, 54 of the hot forming apparatus 30, the method includes stamping the heated preforms 26 between the dies 52, 54 to form a plurality of the shaped portions 20. The stamping step may include simultaneously forming one of the preforms 26 into a plurality of shaped parts 20 using the plurality of cavities 56 in the hot forming apparatus 30. The method subsequently includes cooling each of the shaped parts 20 while the shaped parts 20 are disposed in the cavities 56 of the hot forming apparatus 30. In one embodiment, the cooling step includes cooling at least two of the shaped metal parts 20 in the cavities 56 at different rates to achieve different microstructures in the shaped metal parts 20.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings and may be practiced other than as specifically described while within the scope of the appended claims.

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It is stated that in relation to

INDUSTRIAL method known by the applicant to carry out the aforementioned invention, is the one that is clear from the present description of the invention.

The invention having been described above, the content of the following claims is claimed as property.