Abstract
One or more electro-hydraulic forming tools are operated by a press and provide formed parts to a trimming operation. A locking mechanism holds the die against the chamber during the electro-hydraulic forming (EHF) discharge. The lock may be a pin or clamp. One method of manufacturing an article includes providing three EHF tools that feed a single trimming press on a line. An alternative embodiment discloses a single EHF tool that supplies parts on a production line to an electro-hydraulic (EH) trimming tool. An electro-hydraulic pulse generator may be used to provide a stored charge to the EHF tool and the EH trimming tool.
Claims
1. A method of manufacturing an article with a plurality of electro-hydraulic forming (EHF) tools comprising: clamping a blank separately onto each one of a plurality EHF tools in a progressive sequence; and switching a connection to a single pulse generator; discharging each of the plurality of EHF tools to sequentially form a plurality of shaped parts; and trimming the plurality of shaped parts sequentially in a single, separate trim press.
2. The method of claim 1 wherein the plurality of EHF tools include three EHF tools and three one-sided dies that are operated by three presses, wherein the progressive sequence further comprises operating the presses in a repeating order.
3. The method of claim 2 wherein a cycle time for the trim press is about one-third of a cycle time for each press.
4. The method of claim 1 wherein a cycle time for the trim press is about equal to a multiplication of a cycle time for each press and the reciprocal of the number of the plurality of presses.
5. The method of claim 1 further comprises: filling a chamber defined by each of the EHF tools with water; evacuating air from each of the EHF tools prior to the discharging step; and draining the water from each of the EHF tools.
6. The method of claim 5 wherein the time required for the clamping step, the filling step, the evacuating step, the discharging step and the draining step is a multiple of the time required for trimming the shaped parts in the trim press that corresponds to the number of EHF tools.
7. The method of claim 1 wherein the discharging step further comprises multiple discharges of each of the EHF tools to complete forming the part shape.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) FIG. 1 is a diagrammatic cross-section view of an electro-hydraulic forming tool in a press;
(2) FIG. 2 is a diagrammatic cross-section view of an alternative embodiment of an electro-hydraulic forming tool in a press;
(3) FIG. 3 is a diagrammatic electrical schematic showing three electro-hydraulic forming tools that are selectively connectable to a bank of capacitors;
(4) FIG. 4 is a flowchart of a press line including three electro-hydraulic tools on a line that includes a single trimming press;
(5) FIG. 5 is a forming operation and a trimming operation diagram illustrating an example of a press line operation sequence that may be accomplished in accordance with the process flowchart of FIG. 4; and
(6) FIG. 6 is a flowchart of an alternative embodiment of a press line layout with a single EHF tool and a single EH trimming tool.
DETAILED DESCRIPTION
(7) While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the disclosed apparatus and method. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure as claimed. The features of various implementing embodiments may be combined to form further embodiments of the disclosed concepts.
(8) Referring to FIG. 1, an electro-hydraulic forming (EHF) tool 10 is shown disposed in a press 12 that is preferably a hydraulic press. A blank 16 is shown in the EHF tool 10. The blank 16 is disposed on top of an EHF vessel 18 that defines a chamber 20. A conductive liquid 22, such as water, is contained within the chamber 20. A first electrode 24 and a second electrode 26 are received in the EHF vessel 18 with the first and second electrodes 24 and 26 defining a discharge gap 28 within the chamber 20.
(9) A one-sided die 30 defines a die cavity 32. The blank 16 is formed into the die cavity 32 during the EHF forming process. The press 12 includes a movable platen 34. The one-sided die 30 is secured to the movable platen 34 that moves the one-sided die 30 into and out of engagement with the EHF vessel 18. A pair of locking pins 36, or wedges, are provided to lock the movable platen 34 to the press 12. A hydraulic ram 38 is provided to move the movable platen 34 in a reciprocating manner relative to the EHF vessel 18. The locking pins 36 lock the one-sided die 30 to the press 12 when the ram 38 has moved the movable platen 34 carrying the one-sided die 30 into position to clamp the blank 16 to the EHF vessel 18. The locking pins 36 hold the one-sided die 30 against the EHF vessel 18 during the EHF pulses.
(10) Referring to FIG. 2, an alternative embodiment of an EHF tool 10 in a press 12 is illustrated. For brevity, components that are similar to the embodiment of FIG. 1 are referred to by the same reference numerals in FIG. 2. The EHF tool 10 is shown disposed within a press 12. A blank 16 is placed on an EHF vessel 18 over a chamber 20 that contains a liquid 22. A first electrode 24 and a second electrode 26 are inserted into the chamber 20 and define a discharge gap 28. A one-sided die 30 defines a die cavity into which the blank 16 is formed by the EHF tool.
(11) With continued reference to FIG. 2, a first clamp 40 and a second clamp 42 are moved into engagement with the EHF tool 10 and one-sided die 30 on opposite sides of the press 12. A hydraulic ram 44 links the first and second clamps 40 and 42 to the press 12. Each of the clamps 40 and 42 include a sidewall 46 that is shown connected to the hydraulic ram 44. An upper stop 48 engages the one-sided die 30 and a lower stop 50 engages the EHF vessel 18. The upper stop 48 and lower stop 50 are provided on the upper side of the sidewall 46 and the lower side of the sidewall 46. The upper stop 48 and lower stop 50 hold the one-sided die 30 against the EHF vessel 18 during one or more EHF pulses.
(12) Referring to FIG. 3, an electrical diagram is provided for actuating three EHF forming tools 10 in sequence. A power source 52 provides power to charge a bank of capacitors 54. The bank of capacitors 54 may also be referred to as a stored charge device or a pulse generator for the EHF tools 10. A switch 56 is shown connecting the bank of capacitors 54 to the left-most EHF tool 10 in FIG. 3. The switch 56 may selectively connect the bank of capacitors 54 to each one of the three EHF tools 10. The switch 56 is part of the controller (not shown) for the system. Each of the EHF tools 10 have a positive terminal 58 and a negative terminal 60. Alternatively, a single negative electrode may be provided within each tool 10 that is selectively connected to ground
(13) With continued reference to FIGS. 1-3, FIG. 4 illustrates a production line including three EHF tools. For brevity, components that are similar to the embodiment of FIG. 1 are referred to by the same reference numerals in FIG. 3. Press loading robots 62 are illustrated with each robot 62 feeding a clamping press with an EHF tool at 64. While three robots 62 are shown, it may be possible to use a single robot to load all three of the EHF tools 10 at 64. An EHF pulse generator 66, such as for example the bank of capacitors 54 shown in FIG. 3, is illustrated at 66 that provides a pulse sequentially to each of the EHF tool at 64. The pulse generator provides a pulse within each chamber 20 to cause the liquid 22 to form a plasma discharge shockwave that forms the blank 16 into die cavity 32 of the one-sided die 30. After the part is formed by one or more EHF pulses, a press unloading robot unloads each of the EHF tools at 64. The robot unloads the part to a blank post 70 that comprises a fixture disposed between the EHF tool and the next step on the production line. While three robots 68 are shown, it may be possible to use a single robot to unload all three of the EHF tools 10 at 64. A trim press loading robot at 72 takes the blank 16 and loads the trim press at 74. A trim press unload robot 76 is provided for unloading the trim press 74. The trim press unload robot 76 loads a rack or other device for transporting parts at 78. The parts are then checked according to quality control standards at 80.
(14) Referring to FIG. 5 with continued reference to FIGS. 1-4, a forming and trimming diagram 82 is presented that corresponds to a forming and trimming operation as described with reference to FIG. 4. According to the diagram 82, three EHF presses are referred to as EHF press 1, EHF press 2 and EHF press 3. All three feed parts to a trimming press. In the first phase of the cycle, blank 1 is loaded into the EHF tool, the EHF tool is clamped and the chamber is filled with liquid. At the same time, EHF press 2 is in the process of draining the chamber, unclamping the tool and unloading part 2. At the same time in EHF press 3, the part is formed and, for example, five EHF pulses are used to form part 3. It should be understood that a different number of EHF pulses may be used to form part 3. At the same time, trim part 1 is trimmed. Trim part 1 was formed in a previous cycle of the EHF tool 10 and is loaded into the trim press from the blank post 70.
(15) In the next phase of the cycle, the EHF press 1 forms a part by discharging five EHF pulses in the chamber 20 of the EHF vessel 18. EHF press 2 is loaded with blank 2, the tool is clamped and the chamber is filled with liquid. EHF press 3 is drained, the tool is unclamped and part 3 is unloaded to the blank post 70. The trimming press trims part 2.
(16) In the third phase of the cycle, EHF press 1 is in the process of draining the chamber, clamping the tool and unloading part 1. EHF press 2 is connected to the source of stored charge and five EHF pulses are used to form part 2. During this time period, blank 3 is loaded into EHF press 3, the tool is clamped and the chamber is filled with liquid. The trimming press in this time period trims part 3 that was previously received from EHF press 3.
(17) The timing of the press cycle is divided into 12 second periods and the total elapsed cycle time is shown at the bottom of FIG. 5 to be 12 seconds for the first phase, 24 seconds after the second phase and a total of 36 seconds after the third phase.
(18) Referring to FIG. 6, an alternative embodiment is provided that shows a partial operation sequence for a lower rate production line that includes a single EHF tool and a single EH trimming tool. The process described with reference to FIG. 6 begins with a robot at 84 loading a clamping press having an EHF tool at 86. An EHF pulse generator 88 is connected to the EHF tool and the EH trimming tool to provide electro-hydraulic pulses to the EHF tool and the EH trimming tool. A robot 90 unloads the part from the clamping press at 86. The robot moves the part to a blank post at 92 that holds the part until a robot takes the part from the blank post 92 and a trim press load robot loads at 94 it into the clamping press at 96 that is provided with electro-hydraulic trim tools at 96. The part is trimmed in a clamping press with electro-hydraulic trimming tools at 96. A trim press unload robot 98 unloads the part from the clamping press after trimming with the EH trimming tools at 96. The robot 98 loads the parts into a part transportation device, such as a rack, crate or carton at 100. The parts are inspected at quality control at 102. It should be noted that the quality control step may be conducted either on the manufacturing line before loading into the rack at 100 or may be performed at the point at which the racks are unloaded in an assembly facility.
(19) While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the disclosed apparatus and method. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure as claimed. The features of various implementing embodiments may be combined to form further embodiments of the disclosed concepts.
