22 and the film material 80 made of resin. The film material 80 is provided on the outer peripheral portion of the MEA 22. Examples of the material of the film material 80 include the same materials as those of the resin film 24 described above. The outer end of the resin film 24 is positioned inward of the outer end of the film material 80.

As shown in FIG. 4, the press working apparatus 10 performs press working on the film material 80 as the workpiece W. Specifically, the press working apparatus 10 forms the plurality of passage holes 40 and the plurality of positioning holes 42 in the film material 80 and trims the outer perimeter of the film material 80 into a predetermined shape, thereby manufacturing the above-described resin film 24 (framed MEA 16).

The press working apparatus 10 includes a first die 90 and a second die 92 which are arranged to face each other. The first die 90 is a lower die (fixed die) made of metal. The second die 92 is an upper die (movable die) made of metal. The second die 92 is movable in the vertical direction.

The first die 90 includes a die plate 94, a primary die 96, a secondary die 98, and a first biasing member 100. The primary die 96 is fixed to the die plate 94. A plurality of clearance holes 102 are formed in the primary die 96. Specifically, in the primary die 96, the same number of clearance holes 102 as the number (six) of the passage holes 40 are formed in a shape corresponding to the shape (for example, a quadrangular shape) of the passage holes 40. In addition, in the primary die 96, clearance holes 102 having a shape corresponding to the shape (circular shape) of the positioning holes 42 are also formed in the same number as the number (two) of the positioning holes 42. The clearance holes 102 communicate with the outside through, for example, holes 103 formed in the die plate 94.

The primary die 96 includes a die body 104 and a plurality of protrusions 106. The die body 104 has a flat upper surface 108. A first trimming cutter 110 is provided at an upper outer corner of the die body 104.

The first trimming cutter 110 may be integrally formed with the die body 104. In other words, the first trimming cutter 110 may be formed by thermal spraying or weld overlaying of a hard material on the die body 104.

The plurality of protrusions 106 protrude upward from the upper surface 108 of the die body 104. Each protrusion 106 extends entirely around the upper end of each of the plurality of clearance holes 102. The protruding end surface 112 of the protrusion 106 is positioned above the upper surface 108 of the die body 104. The protruding end surface 112 of the protrusion 106 is flat. The protruding end surface 112 of the protrusion 106 is a first support surface 114 that supports a lower surface of the film material 80 in an adjacent portion 113 adjacent to a portion to be punched out by a piercing punch 122 to be described later. The adjacent portion 113 corresponds to the hole edge portion 54 of the resin film 24. A first piercing cutter 116 is provided at an upper inner corner of the protrusion 106. The upper end of the first piercing cutter 116 is positioned above the upper end of the first trimming cutter 110.

The first piercing cutter 116 may be integrally formed with the protrusion 106. In other words, the first piercing cutter 116 may be formed by thermal spraying or weld overlaying of a hard material on the protrusion 106.

The secondary die 98 is arranged outside the primary die 96. The secondary die 98 may extend around the primary die 96. The secondary die 98 has a second support surface 118 that is flat and supports the outer peripheral portion of a first surface 80a that is one surface of the film material 80. The second support surface 118 faces the second die 92 (upward direction).

The first biasing member 100 biases the secondary die 98 upward. The first biasing member 100 is, for example, a spring. The first biasing member 100 is disposed between the secondary die 98 and the die plate 94. In the initial state of the press working apparatus 10, the second support surface 118 protrudes above the first support surface 114 by a predetermined length L1. In FIG. 4, the predetermined length L1 is shown in an exaggerated manner.

The second die 92 includes a punch plate 120, a plurality of piercing punches 122, a holder 124, a second biasing member 126, and a plurality of pressing members 128. The punch plate 120 is vertically movable along a guide pin (not shown).

The piercing punches 122 are fixed to the punch plate 120. The plurality of piercing punches 122 are positioned above the plurality of clearance holes 102. Specifically, on the punch plate 120, the piercing punches 122 having a shape corresponding to the shape (for example, a quadrangular shape) of the passage holes 40 are disposed in the same number as the number (six) of the passage holes 40. In addition, on the punch plate 120, the piercing punches 122 having a shape corresponding to the shape (circular shape) of the positioning holes 42 are also disposed in the same number as the number (two) of the positioning holes 42. Each piercing punch 122 is inserted into respective one of the clearance holes 102 when the second die 92 moves toward the first die 90. A second piercing cutter 130 is provided at a lower corner of the piercing punch 122.

The second piercing cutter 130 may be integrally formed with the piercing punch 122. In other words, the second piercing cutter 130 may be formed by thermal spraying or weld overlaying of a hard material on the piercing punch 122.

The holder 124 is positioned above the secondary die 98. The holder 124 extends so as to oppose the secondary die 98. The holder 124 has a flat pressing surface 132 that comes into contact with the outer peripheral portion of the second surface 80b that is the other surface of the film material 80. The pressing surface 132 extends in parallel with the second support surface 118. The pressing surface 132 extends in a direction perpendicular to the vertical direction (the moving direction of the holder 124). The holder 124 is a trimming punch 134 for trimming the outer perimeter of the film material 80. A second trimming cutter 136 is provided at a lower inner corner portion of the trimming punch 134.

The second trimming cutter 136 may be integrally formed with the trimming punch 134. In other words, the second trimming cutter 136 may be formed by thermal spraying or weld overlaying of a hard material on the trimming punch 134.

The second biasing member 126 pushes the holder 124 downward. The second biasing member 126 is, for example, a spring. The second biasing member 126 is disposed between the holder 124 and the punch plate 120. The second biasing member 126 connects the holder 124 and the punch plate 120 to each other. In the initial state of the press working apparatus 10, the pressing surface 132 protrudes downward from the lower end 138 of the piercing punch 122 by a predetermined length L2.

The pressing members 128 are provided on the punch plate 120. The pressing members 128 are disposed adjacent to the piercing punches 122 in a direction perpendicular to the vertical direction. The pressing member 128 removes, from the second die 92, the resin film 24 caught on the outer peripheral surface of the piercing punch 122 after press working on the film material 80 (finished film material 80). The pressing member 128 includes a cylinder 140, a rod 142, and a pressing plate 146.

A piston (not shown) is provided inside the cylinder 140 in a slidable manner. The piston is vertically slidable inside the cylinder 140 by compressed air supplied into the cylinder 140. A rod 142 is connected to the piston and extends downwardly from the cylinder 140. The pressing plate 146 is connected to the end portion (lower end portion) of the rod 142. The pressing plate 146 is, for example, a flat plate extending in a direction perpendicular to the vertical direction. The pressing plate 146 has a downwardly facing flat knockout surface 146a. In the initial state of the press working apparatus 10, the knockout surface 146a is positioned above the lower end 138 of the piercing punch 122.

The second die 92 is configured so as not to come into contact with the upper surface of the adjacent portion 113 of the film material 80 when the film material 80 is subjected to the press working.

Next, a press working method using the press working apparatus 10 will be described.

As shown in FIG. 5, the press working method includes a placing step, a gripping step, a piercing step, a trimming step, and a separating step.

In the press working method, as shown in FIG. 4, the workpiece W is placed on the first die 90 in the placing step (step S1). At this time, the first surface 80a of the film material 80 is placed on the first support surface 114 and the second support surface 118. In other words, in the placing step, the film material 80 is placed on the protruding end surface 112 (the first support surface 114) of the protrusion 106 so as to straddle the protrusion 106 around the inner hole (the clearance hole 102).

Subsequently, the second die 92 (punch plate 120) of the press working apparatus 10 is lowered toward the first die 90. Then, the gripping step (step S2), the piercing step (step S3), and the trimming step (step S4) are sequentially performed.

To be specific, when the second die 92 is lowered, as shown in FIG. 6, the pressing surface 132 of the holder 124 (the trimming punch 134) comes into contact with the outer peripheral portion of the second surface 80b of the film material 80. When the second die 92 is further lowered, the secondary die 98 pressed downward by the holder 124 moves downward while compressing the first biasing member 100. At this time, the inner peripheral surface of the secondary die 98 slides on the outer peripheral surface of the die body 104. The holder 124 receiving the reaction force from the secondary die 98 moves toward the punch plate 120 (upward with respect to the piercing punch 122) while compressing the second biasing member 126. As a result, the outer peripheral portion of the film material 80 is firmly held between the secondary die 98 and the holder 124 (gripping step).

In the gripping step, because the reaction force of the compressed first biasing member 100 and the reaction force of the compressed second biasing member 126 act as a gripping force on the outer peripheral portion of the film material 80, the outer peripheral portion of the film material 80 is firmly gripped by the secondary die 98 and the holder 124.

Thereafter, as shown in FIG. 7, the piercing punch 122 presses the second surface 80b of the film material 80 downward. Then, by a shearing force acting on the film material 80 between the first piercing cutter 116 and the second piercing cutter 130, holes (the passage holes 40 and the positioning holes 42) having shapes corresponding to the shapes of the piercing punches 122 are formed in the film material 80 (piercing step). In other words, the piercing punches 122 punch out the film material 80 placed on the protruding end surfaces 112 of the protrusions 106. Thus, the passage holes 40 and the positioning holes 42 are formed in the film material 80.

At this time, the secondary die 98 pushed by the holder 124 further moves downward while compressing the first biasing member 100. In addition, because the upper end of the first piercing cutter 116 is positioned above the upper end of the first trimming cutter 110, the film material 80 is not cut by the first trimming cutter 110 during the piercing step. The punched portions (scraps) are discharged from the clearance holes 102 and the holes 103.

Subsequently, as shown in FIG. 8, the first trimming cutter 110 comes into contact with the first surface 80a of the film material 80. Then, a shearing force acts on the film material 80 between the first trimming cutter 110 and the second trimming cutter 136, so that the outer peripheral portion of the film material 80 is cut off (trimming step). The trimming step is initiated after completion of the piercing step. With the completion of the trimming step, the resin film 24 is produced. During the trimming step, the piercing punches 122 pass through the holes (the passage holes 40 and the positioning holes 42) formed in the film material 80 and are inserted into the clearance holes 102 in the primary die 96.

When the trimming step is completed, the second die 92 is moved upward as shown in FIG. 9. At this time, the inner surfaces of the holes (the passage holes 40 and the positioning holes 42) formed in the resin film 24 may be caught by the outer peripheral surfaces of the piercing punches 122. Therefore, the separating step is performed while moving the second die 92 upward. In the separating step, compressed air is supplied to the cylinder 140 to cause the pressing plate 146 to advance downward. Then, the resin film 24 is pressed downward by the pressing plate 146, so that the resin film 24 is removed from the piercing punches 122. At this time, in the separating step, the film material