HOT SHEET METAL FORMING BY GAS AND DIRECT QUENCHING

Abstract

A hot forming by gas and direct quenching method and apparatus are disclosed. One method of using the system includes a heating step, a forming step, and a direct quenching step. This method increases the quenching speed and allows common steels with high critical cooling rate to be hot formed and quenched. This method reduces or eliminates the need for a furnace and/or the coating of the workpiece prior to the forming, as well as the removal of the coating after the forming. Furthermore, by using a hot gas containing carbon or nitrogen, the workpiece may be case hardened after the heating, forming and quenching steps.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority to an Iran Application Serial Number 139550140003006618 filed on Aug. 23, 2016, which is incorporated by reference herein in its entirety.

TECHNICAL FIELD

The present disclosure relates generally to a method and apparatus for forming a metal plate. More specifically, the present application relates to a method and apparatus for hot forming with a hot gas and direct quenching a metal plate.

BACKGROUND

Weight reduction and improvement of crash safety in automotive and transportation industries are of special importance, as these features lead to lower fuel consumption and environmental emissions. To meet these requirements, the use of a hot stamping process for the production of ultra-high strength components in the automotive industry has been steadily increasing. In conventional hot stamping methods, stamped parts are held at the bottom ‘dead center’ of a press for about ten seconds for cooling. In these cases, the productivity is relatively low. In addition, a special type of steel that includes boron is necessary to lower the critical cooling rate.

SUMMARY

This summary is intended to provide an overview of the subject matter of the present disclosure, and is not intended to identify essential elements or key elements of the subject matter, nor is it intended to be used to determine the scope of the claimed implementations. The proper scope of the present disclosure may be ascertained from the claims set forth below in view of the detailed description below and the drawings.

In one general aspect, the present disclosure describes a hot sheet metal forming with gas and direct quenching system. In one implementation, the system includes a gas chamber, a workpiece disposed above the gas chamber, a die disposed above the workpiece, where the die includes a die cavity. The system also includes a hot gas, where the hot gas enters the die cavity through a die inlet and exits the die cavity through a die outlet, and where the hot gas enters the gas chamber through a gas chamber inlet and exits the gas chamber through a gas chamber outlet. Furthermore, the system has a plurality of nozzles disposed within the gas chamber, where a fluid or mist can be injected into the gas chamber through the plurality of nozzles.

The above general aspect may include one or more of the following features. In one example, the fluid or mist includes a mixture of water and dissolved air. In addition, in some cases, the workpiece can include a steel sheet or a composite of plain-carbon steel and low-carbon steel. In some implementations, the hot gas contains carbon and/or nitrogen. In another example, the workpiece includes a material selected from the group consisting of aluminum alloys, titanium alloys, and magnesium alloys. Furthermore, the workpiece may be configured to be moved manually or automatically in order to change or adjust a distance between the workpiece and the die, such that the system includes an adjustment mechanism to readily control or change the distance between the workpiece and the die. In one case, the nozzles are spaced apart from one another.

In another general aspect, the present disclosure describes a hot sheet metal forming and direct quenching method. The method includes a heating step, a forming step, and a quenching step. In some implementations, the heating step includes positioning a workpiece between a die and gas chamber, moving a heated gas into a die cavity disposed above the workpiece via a die inlet and out of the die cavity via a die outlet, moving the heated gas into the gas chamber below the workpiece via a gas chamber inlet and out of the gas chamber via a gas chamber outlet, and heating the workpiece by application of the injected heated gas. In addition, the forming step can include circulating the heated gas inside the die cavity via the die inlet and the die outlet, circulating the heated gas inside the gas chamber below the workpiece via the gas chamber inlet and the gas chamber outlet, and forming the workpiece by increasing the gas pressure in the gas chamber and forming the workpiece to the die, the die being disposed above the workpiece. The quenching step can involve closing the die inlet and the gas chamber inlet, opening the second outlet, and de-pressurizing the gas chamber by releasing the heated gas from below the workpiece, opening a plurality of nozzles and injecting a high-pressure cold fluid or mist, and cooling the workpiece by application of the high-pressure cold fluid or mist.

The above general aspect may include one or more of the following features. In one example, the heating step occurs in a furnace that is separate from the gas chamber. In addition, in some cases, the cold fluid or mist is a mixture of water and dissolved air. In other implementations, the workpiece includes a steel sheet, or a composite of plain-carbon steel and low-carbon steel. In some cases the hot gas includes carbon and/or nitrogen. In other implementations the workpiece is selected from the group consisting of aluminum alloys, titanium alloys, and magnesium alloys. In one example, the heated gas includes carbon, while in other cases the heated gas includes nitrogen, or both carbon and nitrogen.

Other systems, methods, features and advantages of the implementations will be, or will become, apparent to one of ordinary skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description and this summary, be within the scope of the implementations, and be protected by the claims

BRIEF DESCRIPTION OF THE DRAWINGS

The drawing figures depict one or more implementations in accord with the present teachings, by way of example only, not by way of limitation. In the figures, like reference numerals refer to the same or similar elements.

FIGS. 1A-1D depict a series of flow charts illustrating implementations of a method of using the disclosed forming and quenching system; and

FIG. 2 illustrates one implementation of a hot gas forming and quenching system.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are set forth by way of examples in order to provide a thorough understanding of the relevant teachings. However, it should be apparent that the present teachings may be practiced without such details. In other instances, well known methods, procedures, components, and/or circuitry have been described at a relatively high-level, without detail, in order to avoid unnecessarily obscuring aspects of the present teachings. The following detailed description is presented to enable a person skilled in the art to make and use the methods and devices disclosed in exemplary embodiments of the present disclosure. For purposes of explanation, specific nomenclature is set forth to provide a thorough understanding of the present disclosure. However, it will be apparent to one skilled in the art that these specific details are not required to practice the disclosed exemplary embodiments. Descriptions of specific exemplary embodiments are provided only as representative examples. Various modifications to the exemplary implementations will be readily apparent to one skilled in the art, and the general principles defined herein may be applied to other implementations and applications without departing from the scope of the present disclosure. The present disclosure is not intended to be limited to the implementations shown, but is to be accorded the widest possible scope consistent with the principles and features disclosed herein.

Stamping refers to the forming of a workpiece (such as a sheet metal or blank) into a desired shape. During hot stamping, heating of the desired workpiece is generally performed in a furnace after which the workpiece is placed in a forming machine. Thus, one hot stamping process can include a series of independent operations such as heating, handling, and forming of the workpiece.

The present disclosure describes a hot sheet metal forming and direct quenching system. In different implementations, the hot sheet metal forming utilizes a gas. For purposes of reference, FIGS. 1A-1D provide a series of flow charts illustrating implementations of a method of using the disclosed hot sheet metal forming and direct quenching system.

As a general overview, it can be understood that in some implementations, the system includes a workpiece, a gas chamber, a die, a die inlet, a gas chamber inlet, a die outlet, a chamber outlet, one or more fluids (such as a gas, liquid, or mixture of them), and a plurality of nozzles. Furthermore, the heating step can be implemented by different methods, such as induction heating, resistive heating, industrial furnaces, and other such methods. In one aspect of the present application, the heating step includes heating by a hot gas. In this method, a hot gas with low pressure is injected into the gas chamber and die cavity to heat both sides of the workpiece. The hot gas enters the die cavity through a die inlet and exits from the die outlet above the workpiece. The hot gas also enters the gas chamber through a chamber inlet and exits from the chamber outlet below the workpiece. Although this method can be slower than other heating methods, it can reduce or eliminates the necessity of using a furnace, the step of coating the workpiece prior to the forming, and the step of removing the coating after the forming. Furthermore, by using a hot gas containing carbon or nitrogen, the workpiece (made of plain-carbon steel and low-carbon steel) may be case hardened after the forming and quenching steps.

In addition, the forming step can include an application of force of high pressure hot gas. The high pressure hot gas enters the gas chamber through the chamber inlet below the workpiece and pushes the workpiece into the die in a substantially continuous manner. As a result, the workpiece forms into the shape of the die. The low pressure hot gas may be injected into the space between the workpiece and the die via the die inlet to help maintain the temperature of the die at a substantially constant temperature. It should be noted that in some implementations the temperature of the workpiece is also maintained around a substantially constant temperature during the forming step by flowing of high pressure hot gas.

During the quenching step, the die and chamber inlets are closed and the die and chamber outlets are opened to permit the high pressure hot gas to at least partially exit. Afterwards, the high-pressure cold fluid or mist enters the gas chamber through a plurality of nozzles. The plurality of nozzles can be located or extend from the pressure chamber in some implementations. In one implementation, each nozzle is arranged at a distance from a neighboring nozzle (spaced apart) relative to one another. In some implementations, the nozzles are arranged such that they extend along a wall or surface of the gas chamber in a manner corresponding to the substantial entirety of the length of the workpiece.

In one implementation, the high-pressure cold fluid or mist can comprise a mixture of water and dissolved air. The turbulent flow regime of the high-pressure cold fluid or mist causes rapid quenching of the workpiece.

It should be noted that the heating step may be done in a separate process and in a furnace, where the furnace is separate from the gas chamber. In these cases, the workpiece should be coated before the heating by an insulator layer to avoid oxidation during heating process. The workpiece may be moved between the furnace and the gas chamber manually or automatically.

In another aspect of the present application, the method and the system presented may be used to form metal sheets other than iron and steel, such as aluminum alloys, titanium alloys, magnesium alloys, etc.

Referring now to FIGS. 1A-1D, for purposes of clarity an overview of an implementation of the method. As shown in FIG. 1A, one implementation of a method of forming a sheet metal using this system generally comprises three steps. In a first step 110, the workpiece is heated. In a second step 112, the workpiece is formed by the system, and in a third step 114, direct quenching of the workpiece occurs. Additional details with respect to each of these steps are provided further below.

Referring now to FIG. 1B, an implementation of a heating step for a workpiece is illustrated in a flow chart. A first step 120 comprises positioning a workpiece between a die and gas chamber. A second step 122 includes moving a heated gas into the die cavity above the workpiece via a die inlet and a die outlet. In some implementations, the die inlet can be located above or below the workpiece along a first end of the die cavity, and the die outlet can be located above or below the workpiece and along a second end of the die chamber. In a third step 124, a heated gas is moved into the gas chamber below the workpiece via a gas chamber inlet and a gas chamber outlet. In some implementations, the gas chamber inlet is located below the workpiece and along the first end of the gas chamber, and the gas chamber outlet is located below the workpiece and along the second end of the gas chamber. A fourth step 126 comprises heating the workpiece by controlling a temperature of the injected heated gases for a duration that the injected heated gases are in contact with the workpiece.

As shown in FIG. 1C, an implementation of a method of forming the workpiece is illustrated in a flow chart. A first step 130 involves circulating the heated gas inside the die cavity via the die inlet and the die outlet. In a second step 132, the heated gas is also circulated inside the gas chamber below the workpiece via the gas chamber inlet and the gas chamber outlet. A third step 134 comprises forming the workpiece by increasing the gas pressure inside the gas chamber and forming the workpiece to the die.

An implementation of a method of quenching is illustrated in a flow chart in FIG. 1D. A first step 140 includes closing the die inlet and the gas chamber inlet. In some implementations the closure of these components can occur very close in time, or in a substantially simultaneous manner. A second step 142 includes opening the second outlet and de-pressurizing the gas chamber by exiting the heated gas from below the workpiece. A third step 144 comprises opening a plurality of nozzles and injecting a high-pressure cold fluid or mist. In a fourth step 146, the workpiece is cooled down by a flowing or application of the high-pressure cold fluid or mist. Further details regarding these steps are disclosed further with respect to the description of the apparatus in FIG. 2 below.

Referring now to FIG. 2, for purposes of clarity, one implementation of a hot stamping and quenching system (“system”) 200 is depicted. In FIG. 2, the system 200 includes a workpiece 216, a gas chamber 220, a die 222, a die inlet 224, a gas chamber inlet 226, a die outlet 228, a gas chamber outlet 230, a hot gas 232, and a plurality of nozzles 234. In one implementation, the die can be disposed or positioned at an adjustable distance from the workpiece, or can be pressed into varying distances from the workpiece.

In different implementations, the heating step (as introduced in FIGS. 1A and 1B above) may utilize different methods, such as induction methods, resistive methods, industrial furnaces, and other heating methods. In one implementation of the present application, the heating step may include heating by application of a hot or heated gas. In one implementation of this method, a hot gas 232 with relatively low pressure is injected into the gas chamber 220 and die cavity 222, which applies heat to both sides of the workpiece 216. The hot gas 232 can enter the die cavity 222 and gas chamber 220 through one or more inlets. For example, in FIG. 2, the hot gas 232 enters the die cavity 222 through die inlet 224 disposed above the workpiece 216 and enters the gas chamber 220 through a gas chamber inlet 226 disposed below the workpiece 216. Although in some cases this method can be slower than some other types of heating methods, it provides the benefit of reducing or eliminating the requirement of using a furnace. Furthermore, in the present method, a coating of the workpiece prior to the forming may not be necessary, nor the step of removing the coating after the forming. In addition, by using a hot gas 232 that comprises carbon and/or nitrogen, the workpiece 216 made of plain-carbon steel and low-carbon steel may also be case hardened after the heating, forming and quenching step.

Following the heating of the workpiece, there follows a forming step (as introduced in FIGS. 1A and 1C above). In some implementations, the forming step may include the use of a forming force associated with the high pressure hot gas 232. The high pressure hot gas 232 enters through the gas chamber inlet 226 below the workpiece 216 and can act to push the workpiece 216 into the die 222 in a substantially continuous manner. As a result, the workpiece 216 begins to form into a shape associated with the die 222. Low pressure hot gas 232 may also be injected into the space between the workpiece 216 and the die 222 via the die inlet 224, and help to keep the temperature of the die 222 substantially constant. Thus, in one implementation, the workpiece 216 is maintained at a substantially constant temperature during the forming step 212 by controlling the temperature of the high pressure hot gas 232.

With respect to the quenching step (introduced in FIGS. 1A and 1D above), in some cases, the die inlet 224 and the gas chamber inlet 226 may close and the second outlet 230 may open to permit the high pressure hot gas 232 to at least partially exit the chamber. Afterwards, high-pressure cold fluid or mist is injected in or is in communication with the gas chamber 220 through a plurality of nozzles 234. In one implementation, the cold fluid or mist can comprise a mixture of water and dissolved air. The turbulent flow regime of the high-pressure cold fluid or mist causes rapid quenching of the workpiece 216.

Furthermore, in different implementations, the heating step disclosed herein can occur as a separate process. For example, the heating step can occur in a furnace, where the furnace is separate from the gas chamber. The workpiece may be moved between the furnace and the gas chamber manually or automatically.

In another aspect of the present application, the method and the system presented may be used to form metal sheets other than iron and steel (for example, aluminum alloys, titanium alloys, magnesium alloys, and other such metals).

While the foregoing has described what are considered to be the best mode and/or other examples, it is understood that various modifications may be made therein and that the subject matter disclosed herein may be implemented in various forms and examples, and that the teachings may be applied in numerous applications, only some of which have been described herein. It is intended by the following claims to claim any and all applications, modifications and variations that fall within the true scope of the present teachings.

Unless otherwise stated, all measurements, values, ratings, positions, magnitudes, sizes, and other specifications that are set forth in this specification, including in the claims that follow, are approximate, not exact. They are intended to have a reasonable range that is consistent with the functions to which they relate and with what is customary in the art to which they pertain.

The scope of protection is limited solely by the claims that now follow. That scope is intended and should be interpreted to be as broad as is consistent with the ordinary meaning of the language that is used in the claims when interpreted in light of this specification and the prosecution history that follows and to encompass all structural and functional equivalents. Notwithstanding, none of the claims are intended to embrace subject matter that fails to satisfy the requirement of Sections 101, 102, or 103 of the Patent Act, nor should they be interpreted in such a way. Any unintended embracement of such subject matter is hereby disclaimed.

Except as stated immediately above, nothing that has been stated or illustrated is intended or should be interpreted to cause a dedication of any component, step, feature, object, benefit, advantage, or equivalent to the public, regardless of whether it is or is not recited in the claims.

It will be understood that the terms and expressions used herein have the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective areas of inquiry and study except where specific meanings have otherwise been set forth herein. Relational terms such as first and second and the like may be used solely to distinguish one entity or action from another without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by “a” or “an” does not, without further constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

The Abstract of the Disclosure is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in various implementations. This is for purposes of streamlining the disclosure, and is not to be interpreted as reflecting an intention that the claimed implementations require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed implementation. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separately claimed subject matter.

While various implementations have been described, the description is intended to be exemplary, rather than limiting and it will be apparent to those of ordinary skill in the art that many more implementations and implementations are possible that are within the scope of the implementations. Although many possible combinations of features are shown in the accompanying figures and discussed in this detailed description, many other combinations of the disclosed features are possible. Any feature of any implementation may be used in combination with or substituted for any other feature or element in any other implementation unless specifically restricted. Therefore, it will be understood that any of the features shown and/or discussed in the present disclosure may be implemented together in any suitable combination. Accordingly, the implementations are not to be restricted except in light of the attached claims and their equivalents. Also, various modifications and changes may be made within the scope of the attached claims.

Claims

1. A hot sheet metal forming and direct quenching system for forming a workpiece, the system comprising: a plurality of nozzles disposed within the gas chamber; and

a gas chamber;

a workpiece disposed above the gas chamber;

a die disposed above the workpiece, the die including a die cavity;

a hot gas, wherein the hot gas enters the die cavity through a die inlet and exits the die cavity through a die outlet, and wherein the hot gas enters the gas chamber through a gas chamber inlet and exits the gas chamber through a gas chamber outlet;

a fluid or mist being injected into the gas chamber through the plurality of nozzles.

2. The system of claim 1, wherein the fluid or mist includes a mixture of water and dissolved air.

3. The system of claim 1, wherein the workpiece includes a steel sheet.

4. The system of claim 1, wherein the workpiece includes a composite of plain-carbon steel and low-carbon steel.

5. The system of claim 4, wherein the hot gas contains carbon and/or nitrogen.

6. The system of claim 1, wherein the workpiece includes a material selected from the group consisting of aluminum alloys, titanium alloys, and magnesium alloys.

7. The system of claim 1, wherein the workpiece is configured to be moved manually or automatically in order to change a distance between the workpiece and the die.

8. The system of claim 1, wherein the nozzles are spaced apart from one another.

9. A hot sheet metal forming and direct quenching method, the method comprising:

a heating step, the heating step comprising: positioning a workpiece between a die and gas chamber; moving a heated gas into a die cavity disposed above the workpiece via a die inlet and out of the die cavity via a die outlet; moving the heated gas into the gas chamber below the workpiece via a gas chamber inlet and out of the gas chamber via a gas chamber outlet; and heating the workpiece by application of the injected heated, gas;

a forming step comprising: circulating the heated gas inside the die cavity via the die inlet and the die outlet; circulating the heated gas inside the gas chamber below the workpiece via the gas chamber inlet and the gas chamber outlet; forming the workpiece by increasing the gas pressure in the gas chamber and forming the workpiece to the die, the die being disposed above the workpiece;

a quenching step comprising: closing the die inlet and the gas chamber inlet; opening the second outlet and de-pressurizing the gas chamber by releasing the heated gas from below the workpiece; opening a plurality of nozzles and injecting a high-pressure cold fluid or mist; and cooling the workpiece by application of the high-pressure cold fluid or mist.

10. The method of claim 9, wherein the heating step occurs in a furnace that is separate from the gas chamber.

11. The method of claim 9, wherein the cold fluid or mist is a mixture of water and dissolved air.

12. The method of claim 9, wherein the workpiece includes a steel sheet.

13. The system of claim 9, wherein the workpiece includes a composite of plain-carbon steel and low-carbon steel.

14. The system of claim 9, wherein the gas includes carbon and/or nitrogen

15. The method of claim 9, wherein the workpiece is selected from the group consisting of aluminum alloys, titanium alloys, and magnesium alloys.

16. The method of claim 9, wherein the heated gas includes carbon.

17. The method of claim 9, wherein the heated gas includes nitrogen.