MXPA00009788A - Method and apparatus for simultaneously performing multiple hydroforming operations - Google Patents

Abstract

A hydroforming apparatus (10) and method for simultaneously performing two or more hydroforming operations includes a frame (12) that is sized to support a plurality of hydroforming dies (14,16) in a stacked relationship. Each of the dies (14,16) includes a pair of cooperating die sections (18,20 and 22,24) having respective recesses (18a,20a and 22a,24a) formed therein that define a die cavity. Hollow tubular blanks (26,28) are inserted between the spaced apart die sections (18,20 and 22,24) of the first (14) and second (16) dies. Next, the ram (30) and the support mechanism (31) are moved downwardly relative to the bed (32) such that the pairs of cooperating die sections (18,20 and 22,24) of the first (14) and second (16) dies engage one another. The Tubular blanks (26,28) are filled with a hydroforming fluid, which expands then into conformance with the respective die cavities (21,25).

Description

APPARATUS FOR SIMULTANEOUSLY MULTIPLE HYDROFORMING OPERATIONS BACKGROUND OF THE INVENTION This invention relates generally to an apparatus for performing a hydroforming operation on a closed channel workpiece. In particular, this invention relates to an improved structure for such a hydroforming apparatus that is capable of simultaneously performing two or more hydroforming operations to decrease cycle time and to increase productivity. Hydroforming is a known metalworking process that uses pressurized fluid to expand a closed channel workpiece, such as a tubular member, outwardly to adapt it to a die cavity having a desired shape. A typical hydroforming apparatus includes a frame having two die sections that are supported thereon for relative movement between the open and closed positions. The die sections have cooperating recesses formed therein which define a die cavity having a shape corresponding to a desired final shape for the workpiece. When moving in the open position, the die sections are separated from each other to allow a workpiece to be inserted inside or to be removed for the die cavity. When the closed position is moved, the die sections are placed adjacent to each other so that they enclose the workpiece within the die cavity. Although the die cavity is usually a little larger than the work piece to be hydroformed, the movement of the two die sections from the open position to the closed position in some cases may cause some mechanical deformation of the hollow member. In any case, the workpiece is then filled with a fluid, typically a relatively incompressible liquid such as igua. The fluid pressure within the workpiece increases to a magnitude at which the workpiece expands outwardly to accommodate the die cavity. As a result, the work piece is deformed to the desired final conformation. Hydroforming is an advantageous process for making vehicle frame components and other structures because it can quickly deform a workpiece into a. complex form desired. In a typical hydroforming apparatus, the two die sections are positioned so that the upper die section is supported on a ram of the apparatus, while the lower die section is supported on a bed of the apparatus. It provides a mechanical or hydraulic actuator for raising the ram and the upper die section upwards, to an open position in relation to the bed and the lower die section, whereby a previously deformed work piece is allowed to be removed from the bed. die cavity and that a new work piece is inserted in it. The actuator also lowers the ram and the upper die section down to the closed position relative to the bed and the lower die section, which allows the hydroforming process to be performed. In order to hold the die sections together during the hydroforming process, a mechanical fastening device is usually provided. The mechanical clamping device mechanically couples the die sections (or alternatively, the ram and the base on which the die sections are held is closed to prevent them from moving apart from each other during the hydroforming process.) Such a move would obviously be undesirable because the shape of the die cavity would be distorted, which would result in unacceptable variations in the final shape of the workpiece.Although it has been found with known hydroforming apparatus it works satisfactorily, it has been found that the use of a die The single hydroforming apparatus within a single hydroforming apparatus is somewhat inefficient from the point of view of time consumption.This is because each operational cycle performed by the hydroforming apparatus involves both a preliminary stage of filling the article that is will hydroformer with the hydroforming fluid before carrying out the process Hydroforming, as well as a subsequent step of emptying hydroforming fluid from the article after performing the hydroforming process. These stages of filling and emptying can consume relatively long periods of time, particularly when the articles to be formed are physically large, as often happens in the case of the manufacture of vehicle frame components. This inefficiency is further exacerbated when the hydroforming apparatus is used to produce products in relatively large volumes, as is the case in the manufacture of vehicle frame components, Therefore, it would be desirable to provide an improved structure for a hydroforming apparatus. that is able to carry out simultaneously two or more hydroforming operations to reduce the operational cycle time and, therefore, increase the total productivity.

BRIEF DESCRIPTION OF THE INVENTION The invention relates to an improved structure for an apparatus for simultaneously performing two or more hydroforming operations. The hydroforming apparatus includes a frame that is dimensioned to hold a plurality of hydroforming dies in a stacked relationship. Each of the dies includes a pair of cooperating die sections having respective recesses formed therein defining a die cavity. The first die section of the first die is preferably mounted on, or otherwise connected to, a movable ram of the hydroforming apparatus for movement therewith. The second die section of the first die is preferably connected to or integrally formed with the first die section of the second die, and the combined assembly is preferably held in a support mechanism of the hydroforming apparatus for movement therewith. The second die section of the second die is preferably connected to or integrally formed with a stationary bed of the hydroforming apparatus. Initially, the ram moves upwardly relative to the bed so as to place the first die section of the first die in a further uppermost position spaced relative to a second die section of the second die. At the same time, the support mechanism also moves upward relative to the bed so that it places the second die section of the first die and the first die section of the second die in a separate intermediate position in relation to both the first section of trocnel of the first die as the second die section of the second die. Then, hollow tubular preforms are inserted between the die sections separated from the first and second dies. Then, the ram and the support mechanism move downwardly relative to the bed so that the pairs of cooperating die sections of the first and second dies are coupled together. The end feed cylinders are then moved laterally in engagement with the ends of the tubular preforms to facilitate filling them with a hydroforming fluid. The fluid pressure is then increased within the tubular preforms to such an extent that the tubular preforms expand outwardly in accordance with the respective die cavities. Therefore, the hydroforming apparatus is capable of simultaneously performing two or more hydroforming operations to decrease the total amount of operational cycle time and therefore increase overall productivity. Several objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a side elevational view of the hydroforming apparatus including a plurality of separate dies according to this invention, wherein the hydroforming apparatus is illustrated in an open position prior to the start of an operational cycle of the hydroforming process.

Figure 2 is a side elevational view of the hydroforming apparatus illustrated in Figure 1, wherein the hydroforming apparatus is illustrated in a closed position but even before the start of the hydroforming process. Figure 3 is a side elevation view of the hydroforming apparatus illustrated in Figure 1, wherein the hydroforming apparatus is illustrated in the closed position after the start of the hydroforming process. Figure 4 is an enlarged sectional elevation view of a portion of the hydroforming apparatus taken along line 4-4 of Figure 3. Figure 5 is a schematic, free-body diagram of a portion of the apparatus of hydroforming that is illustrated in figures 1 to 4 which schematically shows the distribution of the forces that are generated during the hydroforming process.

DETAILED DESCRIPTION OF THE PREFERRED MODALITY Referring now to the drawings, an apparatus, indicated generally with the numeral 10, is illustrated in Figures 1 to 4 for carrying out a hydroforming process in accordance with this invention. The apparatus 10 includes a frame 12 that is dimensioned to hold a plurality of hydroforming dies, two of which are generally indicated by the numerals 14 and 16, in a vertically oriented relationship. Although this invention will be described and illustrated in the context of two vertically oriented hydroforming dies 14 and 16, it will be appreciated that this invention can also be implemented with a greater number of such hydroforming dies, if desired. In addition, the hydroforming dies 14 and 16 can be oriented with the hydroforming apparatus 10 in any desired direction other than the vertical direction illustrated for example in a horizontal direction. The first die 14 includes a pair of cooperating die sections 18 and 20 having respective recesses 18a and 20a formed therein. When the two die sections 18 and 20 move together, as shown in Figures 2 and 3, the recesses 18a and 20a formed therein cooperate to define a first die cavity 21 (see Figure 2). Similarly, the second die 16 includes a second pair of cooperating die sections 22 and 24 having their respective recesses 22a and 24a formed therein. When the two die sections 22 and 24 move together, as shown in Figs. 2 and 3, the recesses 22a and 24a formed therein cooperate to define a second die cavity 25 (see Fig. 2). The first die section 18 of the first die 16 is preferably mounted, or connected in some other way, to a first portion of the hydroforming apparatus 10, such as a ram 30, for movement therewith. The second die section 20 of the first die 14 is preferably connected to or integrally formed with the first die section 22 of the second die 16. The combined assembly of the second die section 20 of the first die 14 and the first section 22 of die of the second die 16 is preferably held on a supporting mechanism 31 of the hydroforming apparatus 10 for movement therewith. Alternatively, if the second section The die 20 of the first die 14 and the first die section 22 of the second die 16 are formed as separate pieces, then each can be supported on individual support mechanisms (not shown). Finally, the second die section 24 of the second die 18 is preferably connected to, or integrally with a second portion of the hydroforming apparatus 10, such as a stationary bed 32. Before the start of an operational cycle of the hydroforming apparatus 10, the various components thereof are oriented in the open position as illustrated in Figure 1. As shown in FIG. shows there, the ram 30 moves upward relative to the bed 32 so as to place the first die section 18 of the first die 14 in a further upward position relative to the second die section 24 of the second die. At the same time, the support mechanism 31 also moves upwardly relative to the bed 32 so as to place the second die section 20 of the first die 14 and the first die section 22 of the second die 18 in an intermediate position. separated in relation to both the first die-off section of the first die 14 and the second die section 24 of the second die 18. Subsequently, the first hollow tubular preform 26 is inserted between the die sections 18 and 20 spaced apart from the first die 16, and a second hollow tubular preform 28 is inserted between the die sections 22 and "24 separated from the second die 18. The tubular preforms 26 and 28 illustrated are their substantially of circular cross-sectional shape. Nevertheless, it should be understood that the invention is not limited to any specific form of the tubular preforms 26 and 28, and that the invention can be practiced using hollow members of any shape, insofar as they can be placed within their cavities 21 and 25 of the respective die prior to the hydroforming operation. The tubular preforms 26 and 28 can be manufactured in any conventional manner, for example by rolling a sheet of metallic material in a complete closed tubular configuration and joining the adjacent edges by welding. Alternatively, the tubular preforms 26 and 28 can be manufactured as seamless tubes. If desired, the tubular preforms 26 and 28 can be pre-bent mechanically prior to insertion into the first and second dies 16 and 18 so as to approximate the desired final shapes. It will be appreciated that the two die cavities 21 and 25 can be configured to form the tubular preforms 26 and 28 either in the same form or in two different forms, as desired. After the tubular preforms 26 and 28 have been inserted into the respective die cavities 21 and 25, the ram 30 and the support mechanism 31 move downwardly relative to the bed 32, to the closed position illustrated in FIG. Figure 2. During such closing movement of the first and second dies 16 and 18, the portions of the two tubular preforms 26 and 28 can be mechanically deformed to a certain extent, as shown in Figure 2, although this is not required. When the ram 30 reaches the lowermost position illustrated in Fig. 2, the dies 14 and 16 are placed in a stacked relation between the ram 30 and the bed 32. As used herein, the term "stacked ratio" means that the cooperating die sections of each of the dies are coupled to each other, and further that the adjacent die sections of different dies are coupled together. Therefore, in the illustrated embodiment, the first pair of cooperating die sections 18 and 20 of the first die 14 engage with each other, the second pair of cooperating die sections 22 and 24 of the second die 16 engage with each other, and the second die section 20 of the first die 14 engages with the first die section 22 of the second die 18. At this time, a conventional fastening mechanism (not shown) can be attached so as to maintain the sections 18 and 20 of die of the first die 14 and the die sections 22 and 24 of the second die 18 in the stacked relation illustrated alternatively, if the hydroforting apparatus 10 is adapted from a conventional mechanical shaft, the ram 30 can function as the mechanism of fastening upon moving it to its lower dead center position illustrated in Figure 2, so as to urge or otherwise maintain the die sections 18 and 20 of the first die 14 and l as sections 22 and 24 of die of the second die 18 in the stacked relation illustrated. Then, a first pair of end feeding cylinders 35 and 36 move laterally in engagement with the ends of the first tubular preform 26, while a second pair of end feed cylinders 37 and 38 move laterally in engagement with the ends of the second tubular preform 28, as shown in Figure 4. The end feed cylinders 35, 36, 37 and 38 have respective passages 35a, 36a, 37a and 38a formed therethrough to facilitate filling and emptying the tubular preforms 26 and 28 with a hydroformer fluid, typically a relatively incompressible liquid such as water. The illustrated end feed cylinders 35, 36, 37 and 38 are designed to be representative of any mechanism or mechanisms for sealing the ends of the tubular preforms 26 and 28, to supply pressurized hydroforming fluid to the interiors of the preforms 26 and 28 tubular and for emptying the hydroforming fluid from the interiors of the tubular preforms 26 and 28 at the conclusion of the hydroforming process. In the next stage of the operational cycle of the hydroforming process, the fluid pressure inside the tubular preforms 26 and 28 is subsequently increased to a magnitude such that the tabular preform 26 expands outwardly in engagement with the recesses 18a and 20a formed in the first and second die section 18 and 20 of the first die 16, while the second, tubular preform 28 expands outwardly in engagement with the work 22a and 24a formed in the first and second die sections 22 and 24 of the second die 18. Such expansion causes members 26 and 28 tubular shapes conform to the shape of the die cavities 21 and 25, respectively, as shown in Figures 3 and 4. Preferably, a single source provides the pressurized fluid to each of the tubular preforms 26 and 28 at the same time, so that the respective hydroforming processes can be carried out substantially simultaneously at the same pressures. As a result, the hydroforming apparatus 10 is capable of performing two or more hydroforming operations simultaneously to decrease the total amount of operational cycle time and as a result, increase total productivity. However, the hydroforming process is essentially independent from each other and, therefore, can be carried out with different parameters including times, pressures and the like, if desired. Figure 5 is a free body diagram of a portion of the hydroforming apparatus 10 illustrated in Figures 1 to 4 schematically, showing the distribution of forces that are generated during the hydroforming process. As mentioned above, the introduction of pressurized fluid into each of the tubular members 26 and 28 causes them to expand outwardly in engagement with the respective dies 16 and 18. As a result, forces directed in an opposite manner by the first tubular preform 26 are exerted against the first and second die sections 18 and 20 of the first die 16, and tend to separate by moving them spaced apart from one another, thereby interrupting the ratio of stacked between them.

These opposingly directed separation forces are of equal magnitude to each other and are graphically indicated as FS1 and FS2 of Figure 5. Similar forces are exerted oppositely by the second tubular preform 28 against the first and second punch sections 22 and 24 of the second punch 18, which tend to separate by moving them away from each other, thereby interrupting the stacking ratio between them. These opposingly directed separation forces are also of equal magnitude to one another and are graphically indicated as FS3 and FS4 in FIG. 5.

The frame 12 of the hydroforming apparatus 10 is designed with sufficient strength to absorb these separating forces FS1 and Fs2 to prevent any relative movement between the first and second die sections 18 and 20 of the first die 16, and the first and second die. second die sections 22 and 24 of the second die 18 and in this way the stacked relationship illustrated is maintained. To accomplish this, a first reaction force FR1 is exerted by the ram 30 of the hydroforming apparatus 10 against the first die section 18 of the first die 16. The first reaction force FR1 is of equal magnitude and in the opposite direction to the separation force FS1 and, therefore, avoids any relative movement of the first die section 18 of the first die 16. Similarly, a second reaction force FR2 is exerted by the bed 32 of the hydroforming apparatus 10 against the second die section 24 of the second die 18. The second force FR2 of reactions of equal magnitude and of opposite direction to the separation force FS4 and therefore avoids any relative movement of the second die section 24 of the second die 18. As mentioned above, the hydroforming process is preferably performed on tubular preforms 26 and 28 substantially simultaneously and substantially at the same pre-conditions. internal sions. In this situation, and establishing the assumption that the tubular preforms 26 and 28 are substantially of the same size, then the separation forces FS1 and FS2 generated by the first tubular preform 26 are substantially of the same magnitude as the separation forces FS3 and FS4. generated by the second tubular preform 28. Therefore, the separation forces F32 and FS3 are substantially of the same magnitude and opposite in direction to each other. Therefore, such separation forces FS2 and FS3 substantially cancel each other, which leaves a net force of about 0. Therefore, for the reasons described above, the frame 12 of the hydroforming apparatus 10 should not only be the same. sufficiently strong to be able to absorb the sum of the opposing forces directed in opposite manner FS1 and FS4 to maintain the stacked relationship illustrated between dies 14 and 16. As a result of this cancellation effect, the net force exerted on the frame 12 of the hydroforming apparatus 10 is equal to the sum of the separation forces FS1 and FS4. This net force is no greater than that which would occur if a single die were provided within the hydroforming apparatus 10. Such a single die would exert separation forces that would be the same as the separation forces FS1 and FS4. Therefore, it can be seen that by stacking the first and second dies 14 and 16 in the manner described and illustrated herein, a plurality of tubular preforms 26 and 28 can be hydroformed simultaneously without increasing the net force exerted on the member 12 of frame compared to a conventional single die hydroforming apparatus. Therefore, such a structure is capable of performing two or more simultaneous hydroforming operations to decrease the operational cycle time and, therefore, increase the total productivity without requiring a significant increase in the capacity of the hydroforming apparatus 10. In accordance with the provisions of the patent statutes, the principle and mode of operation of this invention is explained and illustrated in the "preferred embodiment." However, it is to be understood that this invention can be practiced in a manner different from that of the invention. explained and illustrated specifically, without departing from its spirit or scope.

Claims (10)

1. CLAIMS 1. An apparatus for performing a hydroforming operation, comprising: a frame including first and second portions. A plurality of dies held in a stacked relation between the first and second frame portions, each of the dies includes a pair of die sections having respective recesses formed therein which cooperate to define a die cavity when the sections of die are coupled together, each of the die cavities is adapted to receive a tubular preform therein, a means for supplying pressurized fluid within each of the die cavities, the pressurized fluid is adapted to expand the preforms tubular to adapt to the respective die cavities. The apparatus as described in claim 1, characterized in that the first and second frame portions function as a clamping mechanism to maintain the plurality of stacks in stacked relation. 3. The apparatus as described in the claim 1, wherein the first portion of the frame is movable relative to the second portion. The apparatus as described in claim 1, wherein the first portion of the frame is a movable ram, and the second portion of the frame is a stationary bed. 5. The apparatus as described in claim 1, wherein the plurality of dies includes a first punch including first and second punch sections, and a second punch including first and second punch sections. The apparatus as described in claim 1, wherein the first die section of the first die engages the first portion of the frame, and the second die section of the second die is coupled by the second portion of the frame. The apparatus as described in claim 1, wherein the first first die die section is engaged by the first die portion, the second die section of the first die is coupled with the first die second die section. , and the second die section of the second die engages the second portion of the frame. The apparatus as described in claim 7, wherein the frame further includes a support mechanism, and wherein the second die section of the first die and the first die section of the second die are coupled by the support mechanism . . The apparatus as described in claim 7, wherein the second die section of the first die and the first die section of the second tro? Fuel are formed integrally with each other. 10. A method for hydroforming a plurality of tubular members, comprising the steps of: (a) providing a frame including first and second portions; (b) providing a plurality of dies in the frame, each of the dies includes a pair of die sections having respective recesses formed therein that cooperate to define a die cavity when the die sections engage with each other; (c) placing a tubular preform in each of the cavities; (d) orienting the dies in a stacked relation between the first and second frame portions, - and (e) supplying pressurized fluid within each of the die cavities so as to expand the tubular preforms and conform to the cavities of respective die. SUMMARY It provides a hydroforming apparatus for simultaneously performing two or more hydroforming operations including a frame that is dimensioned to hold a plurality of hydroforming dies in a stacked relationship. Each of the dies includes a pair of cooperating die sections having respective recesses formed therein defining a die cavity. Initially, the first die section of the first die is placed in a more superior separate position relative to the second die section of the second die., while the second die section of the first die and the first die section of the second die are placed in a separate intermediate position in relation to both the first die section of the first die and the second die section of the second die. Then hollow tubular preforms are inserted between the die sections separated from the first and second dies. Then, the ram and the support mechanism move downwardly relative to the bed so that the pairs of cooperating die sections of the first and second dies are coupled together. The end feed cylinders then move laterally in engagement with the ends of the tubular preforms to facilitate filling them with a hydroforming fluid. The fluid pressure is then increased within the tubular preforms to a magnitude at which the tubular preforms expand outwardly to accommodate the respective die cavities. Therefore, the hydroforming apparatus is capable of performing two or more hydroforming operations simultaneously to decrease the total amount of operational cycle time and, therefore, increase total productivity.