Method and apparatus to manufacture metallic bipolar plates

摘要

A bipolar plate having a surface structure for a flow field, inner forms such as holes and slots in the plate, and a reference geometry on the outer form thereof is produced by means of a hydraulic fine-blanking press having an at least three-stage progressive die, in the first stage of which a blank is cut partially free from a metal-foil strip, subsequently in a second stage the surface structure is formed in the connected blank via compression-forming using a forming force of at least 2500 to 3500 kN, the inner form, the slots and the reference geometry are formed by way of cutting in, and on, the blank and then, in a third stage, cutting of the outer contour and removal of the finished blank in the form of the bipolar plate are carried out successively in the stroke cycle.

主权项

1. A method for producing a bipolar plate by fine blanking, with a fine blanking press, the bipolar plate comprising a metal-foil plate having a surface structure for a flow field, inner forms in the plate, and at least one reference geometry on a periphery thereof, the method comprising:
feeding a metal-foil strip to a tool of the fine blanking press which opens at a lower dead-center position of a ram of a hydraulic fine-blanking press and closes at an upper dead-center position of the ram of the press; clamping the strip between an upper part of the tool, which comprises at least a forming punch, a cutting and piercing punch and a guide and is mounted on a table of the fine blanking press, and at least one lower part of the tool which comprises a cutting die and performs a stroke between the upper and lower dead-center positions upon closing of the tool; wherein the tool comprises a progressive die configured to perform successive operations, each in a single cycle of a vertical stroke of the press ram thereby cutting and forming a blank from the strip, the successive operations comprising
a first operation comprising cutting the blank partially free in the strip,a second operation performed in a single vertical sequence of the cycle comprising forming the surface structure in the blank by compression-forming using a forming force of 2500 to 3500 kN and producing an inner form of said inner forms in which the inner form comprises at least one opening pierced through the blank, slots and the at least one reference geometry in and on the blank by cutting the blank, anda third operation comprising cutting an outer contour of the blank to finish the blank as the bipolar plate and removing the finished blank from the tool; and wherein a) end-face edges of the blank and, optionally, lateral edges of the blank are cut free of the strip while the blank remains otherwise connected to the strip, b) the tool is opened upon a return stroke of the forming, piercing and cutting punches and the strip comprising the partially cut-free blank is advanced for the compression-forming, piercing and cutting, and the strip is clamped and the compression-forming of the surface structure followed by the producing of the inner form and the reference geometry are carried out sequentially as the ram moves vertically within the second stage while the connection of the blank to the strip is retained, and c) the tool is reopened upon retraction of the forming, cutting and piercing punches to the upper dead-center position and the blank having been cut-free, compression-formed, pierced and cut is advanced to the third working stage for the cutting of the outer contour to complete the bipolar plate, and the blank is separated completely from the strip and falls onto and is removed from the closed tool by a conveyor belt located vertically below a cutting plane of the closed tool.