JP2010018970A - Tile and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tile which prevents "cracking" and "sinking" from occurring around a large number of depressions, even if the depressions are formed on its backside; and to provide a manufacturing method for the tile. <P>SOLUTION: In a first press step, a molding precursor D2 with a thickness L1 is obtained by press-forming a base clay tablet D1 by means of first and second molds 51 and 52. In this case, a depression precursor shape 68 is formed of a first spherical protrusion 62 on the base clay tablet D1. Subsequently, in a second press step, a tile molding with a thickness L2 smaller than the thickness L1 is molded by means of third and fourth molds 71 and 72. In this case, a void 80 is formed between a second spherical protrusion 75 and a depression precursor shape 68 at a stage in which the thickness of a section between press base surfaces of the third and fourth molds reaches the thickness L1; and a hemispherical depression 9 is molded by having the void 80 filled with clay as the thickness of the section between the press base surfaces 73 and 78 of the third and fourth molds 71 and 72 reaches the thickness L2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a tile used for roof finishing of a building structure and a method for manufacturing the tile.

Conventionally, clay tiles have been required to reduce weight and improve yield while maintaining a predetermined strength. For this purpose, for example, a technique such as Patent Document 1 has been proposed. In Patent Document 1, a large number of honeycomb-shaped concave portions are press-molded with respect to a reference surface, and the clay is reduced by the amount of the concave portions to reduce the weight of the clay, and a kind of rib structure called a concave portion. By forming, the strength is also maintained.
Japanese Patent Laid-Open No. 5-230937

However, although the technique of Patent Document 1 can certainly reduce the weight and improve the yield, it still has some problems.
First, in the case where a large number of such honeycomb-shaped recesses are formed, there is a problem that many “cracks” are generated around the recesses at the stage of drying or firing. This is due in part to the recesses with many discontinuous surfaces. This is because a discontinuous surface (specifically, a corner portion) tends to induce cracks. Further, it is considered that this is caused by the fact that the density of clay around the concave portion is not evenly distributed during press manufacturing.
Secondly, there is a problem of “shrinkage” that occurs during firing due to the difference in density. When a special concave portion that is extremely recessed from the periphery as in Patent Document 1 is formed, it is difficult to evenly distribute the clay density to the entire roof tile. This was the cause of the occurrence of “shrinking” on the surface side. In other words, the density of the clay is high at the position of the recess, and the density is relatively low at the periphery of the clay, so that the periphery of the recess falls below the recess at the stage of drying and firing, resulting in a poor appearance of the product. It was.
The present invention has been made paying attention to such problems existing in the prior art. The purpose of the present invention is to provide a roof tile and a roof tile manufacturing method that does not cause “cracking” or “shrinkage” around the recess even when a large number of recesses are formed on the back surface.

In order to achieve the above object, in the first means, a large number of recesses having a continuous inner peripheral surface having a semicircular shape, a semi-elliptical shape or a hyperbolic shape in a cross-sectional line passing through the center are formed on the back surface side of the roof tile. The gist is that it is formed by press molding.
This first means greatly contributes to the original weight reduction and yield. Moreover, since a rib structure is comprised by many recessed parts, intensity | strength is also maintained.
Further, since the concave portion gradually expands radially toward the opening portion, the pressure at the time of molding is dispersed and escapes easily, and the density distribution tends to be uniform. Further, sinking is unlikely to occur because density concentration is prevented. Furthermore, since the inner peripheral surface of the recess has no discontinuous portion, that is, there is no bent corner portion, it is difficult to crack.
Here, “the shape in the cross-sectional line passing through the center is a semicircular shape, a semi-elliptical shape or a hyperbolic shape” is not only a shape in which a sphere or an ellipsoid is cut at a diameter position but also a bottom cut by a plane other than the diameter. This is because a shape such as a round bowl (Bowl) or a shape like a round roof is also included. The hyperbolic shape is a shape that draws a left-right symmetrical upward opening curve such as a dish shape to a U shape. As long as the inner peripheral surface of the recess is continuous, it does not necessarily have a point-symmetric or line-symmetric shape. Moreover, the case where the continuous unevenness | corrugation is formed in the internal peripheral surface is not excluded. In addition, the opening of the recess must be wider than the back of the opening so that at least the mold can be removed during molding.

The second means is characterized in that, in addition to the first means, an embankment raised in a ring shape is formed around the edge of the recess. This contributes to improving the strength, particularly the bending strength of the entire roof tile.
Further, in the third means, in addition to the second means, the surface from the inner peripheral surface of the recess to the outer peripheral surface of the bank portion and the base surface around the bank portion is formed by a continuous curved surface. The gist. This makes it difficult for cracks to form from the recess to the base surface around the recess.
Further, the fourth means is characterized in that, in addition to the second or third means, one of the bank portions is connected to another adjacent bank portion by a rib.
The strength is further improved by these means.

Further, in the fifth means, a first pressing step for obtaining a molded product precursor by press-molding a base clay plate with the first and second molds, and the molded product obtained by the first pressing step. A second press step in which a precursor is press-molded by third and fourth molds to obtain a tile-molded product, and the tile-molded product obtained in the second press step is dried and then fired and tiled. A method for producing a roof tile according to any one of means 1 to 4, comprising a firing step for obtaining
In the first pressing step, a concave precursor shape is formed on the base clay plate by a first protrusion protruding from a back-side press base surface of the first mold, and the first and second molds are formed. The same base clay plate is pressed by the press base surface of the mold to form a molded product precursor so that the space between the base surfaces has a predetermined thickness L1, and in the second pressing step, the third and fourth gold A second projection that protrudes from the back-side press base surface of the third mold while the molded product precursor is pressed by the press base surface of the mold to form a tile molded product having a thickness smaller than the thickness L1. Is placed at a position opposite to the concave precursor shape position of the molded product precursor, and the distance between the press base surfaces of the third and fourth molds that are relatively close to each other reaches the thickness L1. 2 protrusions and the same recess precursor shape A gap is formed between the press base surfaces of the third and fourth molds, and the recess is formed by filling the gap with clay as the gap between the press base surfaces becomes smaller than the same thickness L1. The gist is to do so.

The method of the fifth means is most suitable for producing the roof tiles of the first to fourth means.
In the fifth means, the base clay plate is pressed by the first and second molds in the first pressing step, the concave shape is formed in the base clay plate by the first protrusions, and the first and second The molded product precursor is molded by the press base surface of the mold 2 so that the base surface has a predetermined thickness L1. At this stage, the recessed portion precursor shaped portion is pressed stronger than between the peripheral base surfaces, so that the density is relatively higher than between the peripheral base surfaces.
Next, in the second pressing step, the base surface is pressed by the third and fourth molds so as to be thinner than the thickness L1 so that the molded product precursor becomes a tiled molded product. At this time, the second protrusion protruding from the back-side press base surface of the third mold is arranged at a position facing the concave precursor shape position of the molded product precursor, and the third and fourth molds are relative to each other. In this state, a gap is formed between the second protrusion and the recess precursor shape immediately before pressing and in contact with the molded product precursor, that is, when the thickness L1 is reached. Then, the base surface is pressed by bringing the third and fourth molds close to each other with such a gap. Then, since the space between the base surfaces is strongly pressed, clay moves from the periphery into the gap and is filled. Along with this, the clay at the concave precursor shape portion gradually loosens, and therefore there is no significant difference in the density between the concave portion and the surrounding base surface at the completion of pressing. Therefore, when the tile-molded product formed in such a process is dried and fired, a roof with very few cracks and sink marks can be obtained. Here, the press base surface does not necessarily indicate a universal predetermined portion in the roof tile forming process, but refers to an arbitrary portion that serves as a reference for the distance between the opposing molds when pressing.
Further, in the sixth means, in addition to the fifth means, the first protrusion is a convex body having a semicircular shape, a semi-elliptical shape, or a hyperbolic shape in the outline shape in a cross-sectional line passing through the center. The gist. As a result, the concave precursor shape formed in the first pressing step becomes a surface shape close to the concave portion, which contributes to equalization of clay density in the concave portion formed in the second pressing step.

  According to the first to fourth aspects of the present invention, since a large number of concave portions are formed on the back surface, the weight reduction and the yield of the clay used are good, and the strength can be maintained. Can be provided. According to the inventions of claims 5 and 6, the roof tile can be most suitably manufactured.

Embodiments of the present invention will be described below with reference to the drawings. First, the structure of the flat roof tile 1 manufactured by implementing this invention is demonstrated easily. In the following description, the term “left and right” refers to the direction of girder in a state in which the flat tile 1 is rolled up as a roof tile. In addition, the eaves side in the flow direction of the roof is the front or the bottom, and the ridge side is the back or the top.
As shown in FIGS. 1 to 4, the flat roof tile 1 is a clay plate body fired at a high temperature in a substantially square shape. The flat roof tile 1 is roughly composed of a roof tile body 3 and a heel side edge portion 4 that is formed on the left side of the roof tile body 3. A glaze layer serving as a decorative surface is formed on the upper surface (front surface) of the flat roof tile 1. The upper surface of the roof tile body 3 is defined as a surface-side base surface B1. The roof tile body 3 is a plate body having a constant thickness and having a substantially square planar appearance. Three reinforcing ribs 10 are formed on the back surface of the tile body 3 in parallel and at equal intervals from the head side to the bottom side. An outer side of the reinforcing rib 10 (the farthest side in FIG. 2) arranged on the rightmost side is a side edge 5 on the crosspiece side that is superimposed on the heel side edge 4. The lower surface 5a of the side edge portion 5 is different from the back surface side base surface B2 (see FIG. 5A). That is, the side edge portion 5 is slightly thinner than other portions of the roof tile body 3.
Apart from such a configuration in the left-right direction, the rear end side facing the ridge side of the flat roof tile 1 is the buttocks side and the front end side facing the eaves side is the head side. Although the bottom and the head are not uniformly divided in the flat roof tile 1, in this embodiment, the vicinity of the portion D in FIG. 3 where the upper roof tile 1 overlaps the lower roof tile 1 is the bottom section 7. The vicinity of the Q portion that overlaps with the D portion is defined as a head 8. The head 8 side is formed in a bent shape so that the tip hangs downward.
A large number of hemispherical recesses 9 are formed on the back side of the roof tile body 3. As shown in FIGS. 2, 3, and 5, the concave portion 9 is formed to be depressed toward the front surface side base surface B <b> 1 with respect to the rear surface side base surface B <b> 2. The recesses 9 are arranged in a so-called zigzag pattern on the back surface of the roof tile 3 near the periphery and near the center excluding the lower surface 5 a of the side edge 5.

As shown in FIG. 1 and FIG. 2, a stepped portion 11 is formed at the rearmost end position on the side of the buttocks 7, which is configured in a slightly stepped manner with no glaze layer formed in the left-right direction. On the step portion 11, several dike portions 12 having a complicated shape raised from the surface-side base surface B <b> 1, which is called water return for preventing rainwater from entering, are formed. A pair of left and right through holes 13 are formed in the bank portion 12 a disposed in front of the step portion 11. The through-hole 13 is a hole for driving and fixing a nail into a pier when it is used as a roof tile. A pair of left and right triangular sword portions 14 are formed on the rear side of the step portion 11 so as to protrude downward.
The side edge portion 4 on the heel side is a long rectangular plate piece extending forward and backward at one side edge of the tile body 3, and its upper surface 4 a is at a position slightly lower than the surface side base surface B 1 of the tile body 3. Be placed. Moreover, the lower surface 4b is arrange | positioned in the lower position rather than the back surface side base surface B2. A rear wall portion 15 connected to the bank portion 12 is formed at the upper edge of the side edge portion 4. A low side wall 16 extending in the front-rear direction is formed on the outer side of the side edge 4, and a gutter surrounded on three sides is formed between the rear wall 15 and the side edge 17 on the tile body 3 side.

Next, an example of the manufacturing method of the flat roof tile 1 comprised in this way is demonstrated. In the following description, the molding process will be described specifically with respect to the concave portion 9 of the flat roof tile 1 and its periphery.
As shown in FIG. 6, the manufacturing method of this example includes a first pressing step, a second pressing step, a drying step, and a firing step. In the present embodiment, the first pressing step and the second pressing step are executed in a continuous batch type molding line. The base clay plate D1 is used as a molded product precursor D2 in the first pressing step, and is then used as a tiled product D3 in the second pressing step. Thereafter, the tiled product D3 is subjected to glaze in the drying process to become a dry product called a white background, and finally fired in the firing process to obtain the flat roof tile 1. Below, it demonstrates focusing on a 1st press process and a 2nd press process, and abbreviate | omits description of the drying process and baking process which are well-known processes.
First, the first pressing step will be described.
As shown in FIG. 7, in the first pressing step, the base clay plate D <b> 1 disposed in the first and second molds 51 and 52 is pressed by a known pressing device 50. The base clay plate D1 is sequentially carried into the press device 50 by the robot 53 one by one from the tip of the first conveyor 54, and the molded product precursor D2 press-molded by the two dies 51 and 52 is sent by the robot 53. It is carried out to the 2nd robot 56, and is conveyed by the 2nd press process.

FIG. 8 is an end view corresponding to the position AA in FIG. 3 of the flat roof tile 1 formed by the first and second molds 51 and 52. A first back side press base surface 60 for forming the back side base surface B2 of the flat roof tile 1 is formed on the first mold 51 serving as the lower die. On the side of the first back-side press base surface 60, a back-side sub-press surface 61 for forming the lower surface 4b of the heel side edge 4 is formed. A first spherical protrusion 62 as a first protrusion for forming the recess 9 of the flat roof tile 1 is formed on the first back-side press base surface 60. In addition, the height from the back surface side press base surface 60 of the 1st spherical protrusion 62 to the front-end | tip becomes the amount of biting into the base clay plate D1. This height is defined as a first protrusion amount A (see FIG. 10A). In addition, a concave strip 63 for forming the reinforcing rib 10 is formed so as to intersect with the first spherical protrusion 62. On the first mold 51 side, a lower side plate 64 for sealing the left and right end face directions in the cavity in FIG. 8 is provided.
A first surface-side press base surface 65 for forming the surface-side base surface B1 of the flat roof tile 1 is formed on the second mold 52 serving as the upper die. Moreover, the surface side subpress surface 66 which shape | molds the upper surface 4a of the heel side edge part 4 is formed. On the second mold 52 side, an upper side plate 67 (shown by imaginary lines in the figure) for sealing the front and back end face directions in the cavity in FIG. 8 is provided. The upper side plate 67 is arranged in a direction orthogonal to the lower side plate 64.

Next, the shape change up to the molded product precursor D2 when the flat base clay plate D1 is pressed using the first and second molds 51 and 52 having such a configuration, that is, the movement of the clay. Will be described.
The 2nd metal mold | die 52 is dropped and the base clay board D1 mounted on the 1st metal mold | die 51 is pressed. At this time, as shown in FIG. 10 (a), the first back side press base surface 60 of the second mold 52 is predetermined with the first front side press base surface 65 of the first mold 51. To obtain a molded product precursor D2 in which the concave precursor shape 68 is molded. The distance between the press base surfaces 60 and 65 of the two molds 51 and 52 when the second mold 52 is lowered, that is, the thickness of the molded product precursor D2 is defined as the first thickness L1. The second mold 52 is raised after a predetermined clamping time has elapsed at the position where the first thickness L1 has been reached, and one first pressing step is completed.
At this time, an image of the clay density in the vicinity of the concave precursor shape 68 of the molded product precursor D2 is as shown in FIG. In the vicinity of the recessed portion precursor shape 68 of the molded product precursor D2, the first spherical protrusion 62 is strongly tightened around the most advanced portion, and this portion has the highest density (in the figure, it is expressing). Since the first spherical protrusions 62 are spherical, the amount of pressing decreases toward the periphery, and the density of the clay gradually decreases.

Next, the second pressing process will be described. The second pressing step also has a molding line composed of the same pressing device, conveyor and robot as in FIG. 7 for explaining the first pressing step, and the molded product precursor D2 flows from upstream to downstream. Thus, the tiled product D3 is formed. Since the second pressing step performs the same operation as the first pressing step, detailed description thereof is omitted. Since the second pressing step is different from the first pressing step in that the third and fourth molds 71 and 72 are disposed in the pressing device, the third and fourth molds will be described below. A description will be given specifically for the molds 71 and 72.
FIG. 9 is an end view corresponding to the position AA in FIG. 3 of the flat roof tile 1 formed by the third and fourth molds 71 and 72. A third back surface base surface 73 for forming the back surface side base surface B2 of the flat roof tile 1 is formed on the third mold 71 serving as the lower mold. A sub-press surface 74 for forming the lower surface 4b of the heel side edge 4 is formed on the side of the second back side press base surface 73. A second spherical protrusion 75 as a second protrusion for forming the concave portion 9 of the flat roof tile 1 is formed on the second back-side press base surface 73. The height from the back surface side press base surface 73 of the second spherical protrusion 75 to the tip thereof is defined as a second protrusion amount B (see FIG. 10B). Further, a recess 76 for forming the rib 10 is formed. On the third mold 51 side, a lower side plate 77 for sealing the left and right end face directions in the cavity in FIG. 9 is provided.
The fourth mold 72 serving as the upper mold is formed with a second surface-side press base surface 78 for forming the surface-side base surface B1 of the flat roof tile 1. Further, a surface side sub-press surface 79 for forming the upper surface 4a of the heel side edge 4 is formed. On the fourth mold 72 side, an upper side plate 83 (shown in phantom lines in the drawing) for sealing the front and back end face directions in the cavity in FIG. 9 is provided. The upper side plate 83 is arranged in a direction orthogonal to the lower side plate 77.
The third and fourth molds 71 and 72 are different from the first and second molds 51 and 52 in that the second spherical protrusion 75 is the second as shown in FIGS. The protrusion amount (height) B from the back surface side press base surface 73 is smaller than the first protrusion amount A from the first back surface side press base surface 60 of the first spherical protrusion 62. That is, the first protrusion amount A> the second protrusion amount B.

Next, a description will be given of a shape change up to the tiled molded product D3 when the molded product precursor D2 is pressed by the third and fourth molds 71 and 72 having such a configuration.
The fourth mold 72 is lowered and the molded product precursor D2 placed on the third mold 71 is pressed. At this time, as described above, in the third mold 71, the second spherical protrusion 75 has a smaller protruding amount than the first spherical protrusion 62 of the first mold 51, and therefore, as shown in FIG. At the position where the fourth mold 72 is lowered and the third and fourth molds 71 and 72 have just reached the first thickness L1, the gap between the second spherical protrusion 75 and the concave precursor shape 68 is between A void 80 is formed. Then, the fourth mold 72 is brought close to the third mold 71 until the press base surfaces 73 and 78 are at a predetermined interval, so that the gap 80 is eliminated, as shown in FIG. A tile-molded product D3 in which the recess 9 is press-formed is obtained. The distance between the press base surfaces 73 and 78 of the molds 71 and 72 at this time, that is, the thickness of the tiled product D3 is defined as a second thickness L2. The second mold 52 is raised after a predetermined clamping time has elapsed at the position where the second thickness L2 is reached, and one second pressing step is completed.

At this time, an image of the clay density in the vicinity of the concave precursor shape 68 of the molded product precursor D2 is as shown in FIG. The back portion of the concave precursor shape 68 tightened in the first pressing step has the same density as the surroundings. This is because the press base surfaces 73 and 78 of both dies 71 and 72 are further pressed by advancing from the position where the first thickness L1 is reached to the position where the second thickness L2 is reached. This is because the interstitial clay flows into the gap 80 from the surroundings, or the high density portion is pushed from the surroundings to swell and flow into the gap 80.
If the molding process is finished in a state where the density distribution is not uniform as shown in FIG. 11 (a), and drying and firing are performed, the obtained flat roof tile 1 has a concave portion 9 as shown in FIG. 12 (a). There is a high possibility that a low-density portion around the dent will be depressed (so-called “shrink”), resulting in a defective product. On the other hand, as in this embodiment, by forming the concave portion 9 so as to loosen the concave portion precursor shape 68 portion that was once pressed strongly in the second pressing step, a product that is not inferior like 12 (b) is obtained. Is possible.
With this configuration, in the above embodiment, the flat roof tile 1 is provided with the semi-spherical concave portion 9, so that the weight is reduced and the yield of the clay is improved as compared with the conventional structure. Therefore, the strength can be maintained even when less clay is used.
Further, since the concave portion 9 has a hemispherical shape, the pressing force at the time of molding is easily dispersed, and since there are no angular discontinuous portions on the inner peripheral surface, cracks and tears are less likely to occur. Since the recessed portion 9 is formed so as to loosen the recessed portion precursor shape 68 portion which has been once strongly pressed in the pressing step, cracking and shrinkage are less likely to occur.

It should be noted that the present invention can be modified and embodied as follows.
-As shown in FIG.13 and FIG.14, you may make it form the bank part 81 which raised in the ring shape around the recessed part 9. As shown in FIG. Thereby, the strength of the flat roof tile 1 is improved by the presence of the bank portion 81 in addition to the rib structure by forming the recess 9. Moreover, since the outer peripheral surface of the bank portion 81 is continuously connected to the inner peripheral surface of the recess 9 and there is no discontinuous portion, it is difficult to crack. Furthermore, since each bank part 81 becomes a structure connected with the hexagonal bank part 81 of the circumference | surroundings by the connection rib 82, the intensity | strength is further improved also in this point. The connecting rib 82 may not be provided.
The shape of the periphery of the recess 9 in FIGS. 13 and 14 may be configured such that the tops of the connecting rib 82 and the bank portion 81 are flush with each other, as shown in FIG. That is, the height of the connecting rib 82 illustrated in FIG. 14 may be increased to the height of the bank portion 81.
-It is also possible to implement with the flat roof tile 1 from which the reinforcing ribs 10 are removed from the above-described embodiment as shown in FIGS. In FIG. 16 and FIG. 17, the concave portion 9 that is a main part is indicated by a solid line, and the broken line is shown by a partial design system that is not limited to the external shape of a known roof tile.
-It does not need to be the shape like the recessed part 9 of the said Example, and the arrangement pattern of a recessed part is not limited to said each Example.
The shape of the first spherical protrusion 62 does not have to be hemispherical as described above. The second spherical protrusion 75 is a male shape of the recess 9 and must be hemispherical.
-The shape of a recessed part is not limited to the said Example.
-The above is an example as a manufacturing method, and it is free to change and implement about the shape of a press apparatus, a metal mold | die, a number, a press direction, etc., or a structure which is not directly related to this invention, such as a drying apparatus.
In addition, it is free to implement in a modified form without departing from the spirit of the present invention.

Other technical ideas that can be grasped from the above-described embodiments in order to achieve the object of the present invention will be described below as additional notes.
(1) a first pressing step of obtaining a molded product precursor by press-molding the base clay plate with the first and second molds;
A second press step for obtaining a tile-molded product by press-molding the molded product precursor obtained in the first press step with a third and fourth molds;
A method for producing a roof tile comprising a firing step of drying the roof tile product obtained in the second pressing step and then firing it to obtain a roof tile,
In the first pressing step, a concave precursor shape is formed on the base clay plate by a first protrusion protruding from a back-side press base surface of the first mold, and the first and second molds are formed. Pressing the base clay plate with the press base surface of the mold to mold the molded product precursor so that the base surface has a predetermined thickness L1,
In the second pressing step, the molded product precursor is pressed by the press base surfaces of the third and fourth molds to form a tile molded product having a thickness smaller than the thickness L1, and the third A second protrusion protruding from the back side press base surface of the mold is disposed at a position facing the concave precursor shape position of the molded product precursor, and the press base surfaces of the third and fourth molds are A gap is formed between the second protrusion and the concave precursor shape at the stage of contact with the front and back of the molded product precursor, and the third and fourth molds are relatively close to each other. The tile manufacturing method according to claim 1, wherein the cavity is filled with clay as the tile-molded product is press-molded to form the concave portion.
In the first pressing step, the base clay plate is pressed by the first and second molds, and the concave shape is formed on the base clay plate by the first protrusions, and the first and second molds are pressed. The molded product precursor is molded so that the base surface has a predetermined thickness L1 between the base surfaces. At this stage, the recessed portion precursor shaped portion is pressed stronger than between the peripheral base surfaces, so that the density is relatively higher than between the peripheral base surfaces.
Next, in the second pressing step, the base surface is pressed by the third and fourth molds so as to be thinner than the thickness L1 so that the molded product precursor becomes a tiled molded product. At this time, the second protrusion protruding from the back-side press base surface of the third mold is arranged at a position facing the concave precursor shape position of the molded product precursor, and the third and fourth molds are relative to each other. In this state, a gap is formed between the second protrusion and the concave precursor shape immediately before pressing and in contact with the molded product precursor. Then, the base surface is pressed by bringing the third and fourth molds close to each other with such a gap. Then, since the space between the base surfaces is strongly pressed, the clay moves from the periphery into the gap and is filled. Along with this, the clay at the concave precursor shape portion gradually loosens, and therefore there is no significant difference in the density between the concave portion and the surrounding base surface at the completion of pressing. Therefore, when the tile-molded product formed in such a process is dried and fired, a roof with very few cracks and sink marks can be obtained. In addition, the recessed part here is not limited to the recessed part of the said Example. If a concave precursor shape is formed on the base surface in the first pressing step, and a concave portion is formed by pressing the surrounding base surface while leaving a gap in the concave precursor shape portion in the second pressing step. The shape of the recess is not limited.

The perspective view of the flat roof tile of the Example of this invention. The back side perspective view of the same flat roof tile. The back view of the same flat tile. (A) is a side view of the same flat roof tile, (b) is a rear view of the same flat roof tile. (A) And (b) is an end elevation in the AA line and BB line of FIG. 3, respectively. The flowchart explaining the flow of the process of the Example of this invention. Schematic explanatory drawing explaining the process of arrange | positioning a base clay board between the 1st and 2nd metal mold | die in a press apparatus at the 1st press process, and shape | molding a molded article precursor. The end view corresponding to the AA position of the flat roof of FIG. 3 of the 1st and 2nd metal mold | die used at a 1st press process. The end view corresponding to the AA position of the flat roof of FIG. 3 of the 3rd and 4th metal mold | die used at a 2nd press process. (A) is a partial cross-sectional view of a state in which the molded product precursor is molded with the first and second molds in the first pressing step, and (b) is the third and fourth molds in the second pressing step. FIG. 4C is a partial cross-sectional view of a state immediately before pressing a molded product precursor in FIG. 2C, and FIG. 5C is a partial cross-sectional view of a state in which a tile-molded product is formed with a third and fourth mold in a second pressing step. (A) Explanatory drawing explaining the density distribution state of the clay of the molded product precursor in the stage which the 1st press process was complete | finished, (b) is a mold in the stage where the 2nd press process was complete | finished Explanatory drawing explaining the density distribution state of the clay of the product precursor in an image. (A) is explanatory drawing explaining the malfunction state of the flat roof tile when it burns in the state of Fig.11 (a), (b) demonstrates the favorable state of the flat roof tile when fired in the state of FIG.11 (b). FIG. (A) is the elements on larger scale explaining the back surface shape containing the recessed part of the flat roof of another Example, (b) is an end elevation in CC in (a), (c) is D- in (a). End view at D. FIG. FIG. 14 is an enlarged partial cross-sectional view illustrating the vicinity of one concave portion of the flat roof tile of FIG. (A) is the elements on larger scale explaining the back surface shape containing the recessed part of the flat roof of another Example, (b) is an end elevation in EE in (a). The back side perspective view which represented only the principal part of the flat roof tile of the other Example by the continuous line. The back view which represented only the principal part of the flat roof of another Example with the continuous line.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Flat roof tile, 9 ... Concave part, 51 ... 1st metal mold | die, 52 ... 2nd metal mold | die, 68 ... Recessed precursor shape, 71 ... 3rd metal mold | die, 72 ... 4th metal mold | die, 60,65 , 73, 78 ... Press base surface, 62 ... First spherical projection as the first projection, 75 ... Second spherical projection as the second projection, 80 ... Gap, B2 ... Back side base surface, D1 ... Base clay plate, D2 ... Molded product precursor, D3 ... Tile molded product.

Claims (6)

A roof tile characterized in that a large number of concave portions having continuous inner peripheral surfaces having a semicircular shape, a semi-elliptical shape, or a hyperbolic shape in a cross-sectional line passing through the center are formed on the back surface side of the roof tile by press molding. The roof tile according to claim 1, wherein an embankment raised in a ring shape is formed around an edge of the recess. The roof tile according to claim 2, wherein a surface from the inner peripheral surface of the recess to the outer peripheral surface of the bank portion and the base surface around the bank portion is formed as a continuous curved surface. The roof tile according to claim 2 or 3, wherein the one bank portion is connected to another adjacent bank portion by a rib. A first pressing step of obtaining a molded product precursor by press-molding the base clay plate with the first and second molds;
A second press step for obtaining a tile-molded product by press-molding the molded product precursor obtained in the first press step with a third and fourth molds;
A method for producing a roof tile according to any one of claims 1 to 4, further comprising a firing step of obtaining a roof tile by drying the roof tile product obtained in the second pressing step.
In the first pressing step, a concave precursor shape is formed on the base clay plate by a first protrusion protruding from a back-side press base surface of the first mold, and the first and second molds are formed. Pressing the base clay plate with the press base surface of the mold to mold the molded product precursor so that the base surface has a predetermined thickness L1,
In the second pressing step, the molded product precursor is pressed by the press base surfaces of the third and fourth molds to form a tile molded product having a thickness smaller than the thickness L1, and the third The 3rd and 4th metallic molds which arrange the 2nd projection part projected from the back side press base surface of a metallic mold in the position which counters the above-mentioned crevice precursor shape position of the molding product precursor, and approach relatively When the space between the press base surfaces reaches the thickness L1, a gap is formed between the second protrusion and the concave precursor shape, and the press base surfaces of the third and fourth molds The roof tile manufacturing method according to claim 1, wherein the gap is filled with clay and the recess is formed as the space becomes narrower than the same thickness L1. 6. The roof tile manufacturing method according to claim 5, wherein the first protrusion is a convex body having a semicircular shape, a semi-elliptical shape, or a hyperbolic shape in a cross-sectional line passing through the center.

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