Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D26/00—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces
  • B21D26/02—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces by applying fluid pressure
  • B21D26/033—Deforming tubular bodies
  • B21D26/041—Means for controlling fluid parameters, e.g. pressure or temperature

Definitions

• TITLE METHOD AND APPARATUS FOR SUPPLYING FLUID
• the present invention relates generally to hydroforming processes, and more specifically relates to the handling of fluid for a hycfroforming process.
• the hydrofo ⁇ ning technique in general is based on the utilization of hydraulic fluid under very high pressure to form metal workpieces.
• a common problem experienced in all hydrofo ⁇ ning processes and specifically in the internal hy ⁇ rofon ing of tubular workpieces, is to provide an efficient handling of the fluid that is employed to form a workpiece in a hydroforming tool. Such handling shall secure a rapid supply of hydroforming fluid to the workpiece in order to obtain minimum cycle times for each forming operation.
• the hydroforming processes are therefore considered to be undesirably messy and require additional cleaning work, both with regard to the actual formed workpiece and to the entire hydrofo ⁇ ning equipment.
• An additional problem of the "open" fluid handling is that the fluid is in most cases quite contaminated and must be cleaned or even regenerated before it is used in a new forming process.
• the above mentioned problem of air becoming trapped in the workpiece is particularly common by the supply of hydroforming fluid to a tubular workpiece, especially in cases where the workpiece has bends etc.
• attempts have been made to solve this problem by allowing trapped air to escape around the perimeter of end plugs that have not been finally sealed to the workpiece at this stage.
• the prior art filling procedures do not at all times secure successful venting of all trapped air, especially not in larger workpieces of complex shape.
• the invention provides a solution overcoming the above discussed problems experienced with the prior known techniques.
• the invention provides a method and a system for the efficient supply of fluid to a work- piece to be formed in a hydroforming process, hi such a process low pressure fluid is supplied through inlet means to a working chamber and the pressure of said fluid is then considerably raised for deforming the workpiece against a die.
• vacuum is applied to the working chamber through separate outlet means as low pressure fluid is fed thereto. This application of vacuum is then terminated prior to raising the fluid pressure to the forming pressure, and the outlet means is simultaneously blocked.
• the pre-filling of the working chamber with low pressure fluid will be will speeded-up to a consider- able degree. Since the pre-filling of the working chamber with low pressure fluid conventionally constitutes a considerable part of the complete hydroforming cycle, such a speeded-up fluid supply will have a significant effect on the productivity of the forming technique.
• vacuum is also applied to the working chamber subsequent to the completion of the actual forming step.
• This application of vacuum will speed-up also the fluid discharge from the working chamber, with the resulting further gain in productivity.
• this post-forming vacuum application for discharge purposes may be performed through either the inlet or the outlet means. This will likewise permit handling of the fluid in a closed system throughout the entire hydroforming operation, including fluid supply, foiming and fluid discharge, to thereby minimize contamination of the fluid.
• the post-forming vacuum application is replaced by or combined with an application of pressurized air through one of the inlet or the outlet means or alternatively through the inlet or outlet means that is not used for the vacuum appUcation.
• these measures will speed-up fluid discharge even further and will not least also provide for an automatic clearing of the portion of the workpiece that has been in contact with the hydroforming fluid.
• the fluid supply is directed generally towards a bottom surface of a fluid working chamber whereas the vacuum is applied to an upper portion of the working chamber. This will promote a relatively calm filling and simultaneously an efficient removal of air from the fluid working chamber.
• Fig. 1 is a very schematic illustration of a first basic embodiment of a fluid system according to the invention
• Fig. 2A illustrates the fluid system of fig. 1 in a filling mode
• Fig. 2B illustrates the fluid system of fig. 1 in a forming mode
• Fig. 2C illustrates a further developed method of the invention applied to the fluid system of fig. l;
• Fig. 2D illustrates the fluid system of fig. 1 at the end of a full hydroforming cycle
• Fig. 3 is an illustration corresponding to fig. 2C of a modified second embodiment of the inventive fluid system in the emptying and clearing mode;
• Fig. 4 is a very schematical partial view of a practical embodiment of end closure devices designed for optimum supply of fluid to a working chamber.
• FIG. 1 An exemplary illustrative embodiment of the fluid system of the invention is illustrated in figs. 1 and 2A-D.
• the fluid system is here illustrated as applied to hy ⁇ roforming equipment employed for the internal hydrofoiming of tubular workpieces 1 and comprising a forming tool or die 22 consisting of an upper and a lower tool half 23 and 24, respectively.
• the tool halves 23, 24 each have a recess 23 A, 24A formed in facing surfaces thereof, for receiving the workpiece 1 during the forming operation.
• a press not illustrated, or special clamps as disclosed in our earlier International Patent Application no. WO 01/36123 Al.
• the recesses 23A, 24A of the tool halves 23, 24 form a channel receiving the workpiece 1 and having a shape corresponding to the desired final outer shape of the formed workpiece 1 A (see figs. 2B-2D).
• end closure means 7 and 8 are extended by means of operating means 9 and 10, respectively, until they engage the respective one of opposite ends of the workpiece 1.
• solid lines illustrate the end closure means in their refracted positions whereas dash-dot lines illustrate them in their extended positions engaging the workpiece 1 ends.
• Hydroforming fluid HF is basically supplied to the hydroforming equipment from a main fluid tank 12 that is provided with filter equipment 12A a ⁇ d/or 12B on the pressure and/or return side.
• fluid contamination will be modest and the required filtering capacity will normally be equally low.
• fluid HF is here pumped to a fluid supply tank 16 by means of a fluid pump 14.
• a pressure intensifier 11 fluid inlet means 3 with a fluid supply channel 3 A and the respective connecting fluid lines 13, 15, 17 hydroforming fluid HF is supplied to the workpiece 1 in a manner that will be described more closely below, with reference to figs. 2A-2D.
• Return of fluid from the workpiece 1 to the main tank 12 is similarly performed through fluid outlet means 5 with a fluid discharge channel 5 A, a discharge valve 6, a fluid discharge tank 20 and the respective connecting fluid lines 21, 18, as will likewise be described more closely below.
• a subatmospheric pressure or vacuum V is applied to the fluid outlet means 5 and its schematically indicated fluid channel 5A, to a fluid working chamber 2 formed by the interior of the workpiece 1 and to the fluid inlet means 3 and its schematically indicated fluid channel 3A, as is illustrated in Fig. 2A.
• a vacuum generator 30 such as a vacuum pump
• Fluid LPF at a first low pressure level preferably at or close to atmospheric pressure, is then supplied from the fluid supply tank 16 to the working chamber 2 by opening the fill valve 4.
• the complete filling of the fluid working space 2 with low pressure fluid LPF is performed very quickly.
• the vacuum generator 30 is stopped and the fill 4 and discharge 6 valves are closed, preferably controlled by appropriate sensors, not shown, automatically detecting the complete filling of the fluid working space 2.
• a sensor may for instance be a level sensor detecting a rise in the fluid level of the fluid discharge tank 20 or other appropriate known sensor.
• the application of vacuum V to speed-up the filling of the fluid working chamber 2 will also have the additional favorable effect of reducing the risk that air remains trapped in the working chamber 2. Basically, this removal of air is related to the strength of the vacuum applied to the working chamber 2, so that air is more effectively removed the stronger the applied vacuum is.
• Fig. 2B illustrates the next step of the hydroforming process, namely the actual forming process that is basically performed in a well known manner.
• the pressure intensifier 11 is operated by supplying operating fluid OP thereto.
• the design or operation of the pressure intensifier 11 will not be described in detail herein, but reference may be made our earlier International Patent Application no. WO 01/42662 Al that in detail discloses the design and operation of a pressure intensifier.
• the pressure intensifier 11 raises the pressure of the fluid to a second forming level HPF of often several thousand bar.
• the pressure intensifier 11 is stopped and the high pressure is relieved, in the schematically illustrated example by applying operating fluid OF in a reverse direction to the intensifier 11.
• the vacuum generator 30 is then activated again for supporting the discharge of fluid LPF from the working chamber 2. Specifically, the fill 4 and discharge 6 valves are opened to once more apply the vacuum V to the fluid working chamber, thereby speeding-up also the discharge of fluid HF therefrom. When all fluid HF has been discharged from the product 1A and from the input means 3 and output means 5 the fill 4 and discharge 6 valves are closed again.
• the entire filling, forming and discharge process is performed with a closed fluid system. This promotes cleanliness in and around the hydroforming equipment and of the hydroforming fluid HF.
• the end closure means 7 and 8 With all fluid LPF discharged from the product 1 A and from the input means 3 and output means 5 the end closure means 7 and 8 are retracted from the tubular ends of the product 1 A, as is illustrated in fig. 2D, and finally the formed product 1 A is removed from the hydroforming tool or die 22 that has been opened after completion of the forming process.
• the fill 4 and discharge 6 valves are closed again and fluid is pumped from the fluid discharge tank 20 to the main tank 12 and from the main tank 12 to the fluid supply tank 16.
• the described vacuum supported filling of the workpiece 1 or fluid working chamber2 with low pressure hydroforming fluid LPF will not only considerably speed-up the filling procedure to increase productivity, but will also significantly reduce the risk of air being trapped in the working chamber during high pressure forming.
• the additional vacuum supported discharge of the fluid after forming will even further increase productivity by speeding-up also said fluid discharge.
• FIG. 3 A modified second embodiment of the inventive fluid system is schematically illustrated in Fig. 3 that shows the system in a situation corresponding to that of Fig. 2C.
• the modifications to the system do in effect mainly concern the actual emptying or discharge phase of the process and consists of the addition of a source 19 of pressurized air PA that is connected to the fluid inlet means 3 through an additional air valve 25, the fluid supply tank 16 and the fill valve 4.
• the fluid discharging method differs from the one described in connection with Fig. 2C in that after the high pressure forming is completed and the high pressure has been relieved, the pressurized air source 19 is activated and the air valve 25 is opened essentially at the same time as the vacuum generator 30 is activated and the fill 4 and discharge 6 valves are opened.
• the pressurized air PA is applied through the fluid inlet means 3 whereas the vacuum V for the forced fluid discharge is applied through the fluid outlet means 5.
• the direction of the fluid discharge could be reversed. Specifically, during the fluid discharge phase appropriate valve means, not illustrated, could be employed to redirect the vacuum application to the fluid inlet means 3, through the fluid supply tank 16, and to apply the pressurized air (PA) to the fluid outlet means 5, through the fluid discharge tank (20).
• the invention is not restricted to the use of pressurized air PA in combination with vacuum V for the discharge process, but also covers an embodiment where pressurized air PA alone is employed during the fluid discharge phase and the vacuum is not applied at all for the forced fluid discharge but only for the fluid supply phase.
• Fig. 4 is finally disclosed a modified embodiment according to the invention.
• the modification is illustrated as applied to end closure means 107, 108 similar to those disclosed in connection with the previously described embodiments.
• the embodiment illustrated in Fig. 4 is based on the insight that when performing the forced fluid supply according to the invention, the removal of trapped air from the fluid working chamber 2 is dramatically improved if the infeed of low pressure fluid LPF is directed to a lower part of the fluid working chamber 2 and the application of the vacuum V and therefore the trapped air removal is performed at an upper part of the fluid working chamber.
• infeed slit 107A is part of the fluid supply channel 3A of the input means 3, is connected thereto in or near the center of the end closure means and is directed obliquely downwardly against the lower wall of the working chamber 2.
• a generally fan- shaped output slit 108 A is provided in the second end closure means 108, opening in the upper area of the end closure means close to the outer circumference thereof and thereby close to an upper wall of the working chamber 2, here the upper portion of the inner wall of the workpiece 1.
• the output slit 108 A is part of the fluid discharge channel 5A of the output means 5, is connected thereto in or near the center of the end closure means and is directed obliquely upwardly against the upper wall of the working chamber 2.

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• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Shaping Metal By Deep-Drawing, Or The Like (AREA)
• Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)

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Publications (2)

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• 2003
  • 2003-10-24 WO PCT/SE2003/001653 patent/WO2005039799A1/en not_active Ceased
  • 2003-10-24 EP EP03759131A patent/EP1675695B1/de not_active Expired - Lifetime
  • 2003-10-24 DE DE60327376T patent/DE60327376D1/de not_active Expired - Lifetime
  • 2003-10-24 AU AU2003274862A patent/AU2003274862A1/en not_active Abandoned
  • 2003-10-24 AT AT03759131T patent/ATE429296T1/de not_active IP Right Cessation

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