Gypsum board manufacturing method and manufacturing device

1. A method for producing a gypsum board, the method comprising:

continuously injecting a gypsum slurry into a gap between a pair of upper and lower lining paper sheets while continuously supplying the pair of upper and lower lining paper sheets, so as to form a laminated material; and

allowing the laminated material to pass between a pair of upper and lower forming plates so as to form a molded body having a thickness corresponding to a space between the upper and lower forming plates,

wherein at least one of the upper and lower forming plates comprises:

a plate main body comprising an electrically conductive material; and

an embedded electrode embedded in the plate main body,

wherein the embedded electrode is electrically insulated from the plate main body by an insulator and is embedded so that a portion of the embedded electrode is exposed on a surface of the plate main body, where the plate main body contacts the lining paper sheet,

a circuit is completed by electrically connecting the plate main body and the embedded electrode embedded in the plate main body, and a voltage is applied to the circuit, and

whenever the lining paper sheet adjacent the embedded electrode is cut, the plate main body and the embedded electrode contact with the gypsum slurry, electric current flows in the circuit, and the space between the pair of upper and lower forming plates is expanded until the electric current flows are broken, and thereafter the space between the pair of upper and lower forming plates is restored to the original space.

2. The method for producing a gypsum board according to claim 1 ,

wherein the embedded electrode is embedded in the plate main body at a portion on a downstream side relative to a starting position of forming the gypsum board, where the starting position of forming the gypsum board is defined as one of the following (1) and the following (2), whichever is located at a more downstream side:

(1) a position of an upstream end of either one of the pair of upper and lower forming plates; and

(2) a position of a downstream end of a taper portion if present in an embodiment,

wherein the taper portion is formed on at least one of the pair of upper and lower forming plates,

a plate thickness of the taper portion becomes thinner toward the upstream ends of the forming plates, and

the space between the pair of the forming plates becomes larger toward the upstream ends of the forming plates, corresponding to the plate thickness.

3. The method for producing a gypsum board according to claim 2 ,

wherein the embedded electrode is embedded in the plate main body between the starting position of forming the gypsum board and a position of 50 mm to a downstream side from the starting position.

4. The method for producing a gypsum board according to claim 1 ,

wherein the insulator comprises at least one material selected from the group consisting of phenol resin laminated plates with a cloth base material, phenol resin laminated plates with a paper base material, epoxy resin-impregnated glass fiber cloth, and epoxy resin-impregnated paper.

5. The method for producing a gypsum board according to claim 1 ,

wherein the electrically conductive material is at least one material selected from the group consisting of iron materials, stainless steel materials, and aluminum materials, or a material obtained by applying hard chromium plating thereon.

6. An apparatus for producing a gypsum board, comprising:

a pair of upper and lower forming plates for forming a laminated material,

wherein the laminated material is obtained by injecting a gypsum slurry into a gap between a pair of upper and lower lining paper sheets, and a thickness of the laminated material corresponds to a space between the plates,

wherein at least one of the pair of upper and lower forming plates comprises:

a plate main body comprising an electrically conductive material; and

an embedded electrode embedded in the plate main body,

wherein the embedded electrode is electrically insulated from the plate main body by an insulator and is embedded so that a portion of the embedded electrode is exposed on a surface of the plate main body, where the plate main body contacts the lining paper sheet,

a circuit is completed by electrically connecting the plate main body and the embedded electrode embedded in the plate main body, and

the apparatus further comprises:

an electric current detector, which is electrically connected to the circuit; and

an actuator, which moves at least one of the forming plates, up and down in response to an electric signal from the electric current detector.

7. The apparatus for producing a gypsum board according to claim 6 ,

wherein the embedded electrode is embedded in the plate main body at a portion on a downstream side relative to a starting position of forming the gypsum board, where the starting position of forming the gypsum board is defined as one of the following (1) and the following (2), whichever is located at a more downstream side:

(1) a position of an upstream end of either one of the pair of upper and lower forming plates; and

(2) a position of a downstream end of a taper portion if present in an embodiment,

wherein the taper portion is formed on at least one of the pair of upper and lower forming plates,

a plate thickness of the taper portion becomes thinner toward the upstream ends of the forming plates, and

the space between the pair of the forming plates becomes larger the taper portion toward the upstream ends of the forming plates, corresponding to the plate thickness.

8. The apparatus for producing a gypsum board according to claim 7 ,

wherein the embedded electrode is embedded, in the plate main body between the starting position of forming the gypsum board and a position of 50 mm to a downstream side from the starting position.

9. The apparatus for producing a gypsum board according to claim 6 ,

wherein the insulator comprises at least one material selected from the group consisting of phenol resin laminated plates with a cloth base material, phenol resin laminated plates with a paper base material, epoxy resin-impregnated glass fiber cloth, and epoxy resin-impregnated paper.

10. The apparatus for producing a gypsum board according to claim 6 ,

wherein the electrically conductive material is at least one material selected from the group consisting of iron materials, stainless steel materials, and aluminum materials, or a material obtained by applying hard chromium plating thereon.