JP7697702B2 - Heating and cooking plate - Google Patents

Description

The present invention relates to a cooking plate used in a cooking appliance that heats and cooks food ingredients.

The cooking plate used in cooking appliances for commercial or household use is a hot plate for cooking using energy such as electricity, gas, or charcoal as a heat source, and is used for cooking okonomiyaki, steak, yakiniku, takoyaki, Genghis Khan, baked goods, etc. Metal plates such as steel, cast iron, stainless steel, copper, or aluminum, wire mesh, ceramic plates (including ceramic plates and crystallized glass plates), or non-metallic plates such as stone plates are used as the material for the plate. The main parts are made by casting, forging, machining, etc., and some are assembled using welding or screws. The shape of the cooking surface is made according to the cooking method and the finished shape, and is approximately flat for steak, okonomiyaki, pancakes, etc., perforated flat plates (so-called rostre), wire mesh, or shapes with many irregularities of about several mm for yakiniku and seafood grilling, helmet-shaped for Genghis Khan, etc., and plate-shaped with multiple depressions for sweets such as takoyaki and imagawayaki.

Cooking plates are also molded into square or round shapes in plan view to match the shape of the cooking appliance they will be used in, and they come in a variety of sizes, from small ones measuring around 0.3 m for home use to large commercial cooking counters with long sides exceeding 3 m.

Moreover, most of these cooking plates are roughly flat in shape, and even if they are three-dimensional, they only have grooves cut into the outer periphery of the plate to separate the broth and oils that come with cooking, except for the area where the ingredients are actually placed and cooked, and there are few designs that are primarily designed to save energy.

For example, Patent Document 1 describes the provision of a protection section against backflow (spreading to the back side) of oil juice on the back side. The first backflow prevention section is a zigzag-shaped uneven section in cross section, and the second backflow prevention section is a downwardly convex protrusion. It is assumed that oil juice flows from the opening in the cooking surface of the heat-cooking plate to the back side and spreads, and the second backflow prevention section is provided upstream of that flow, and the first backflow prevention section is provided downstream. The first backflow protection wall is a zigzag-shaped uneven section with a triangular wave-shaped cross section within the range that reduces the thickness of the plate, and the term unevenness means that there are multiple consecutive concave and convex sections. The second backflow protection wall is a downwardly convex shape that increases the thickness of the heat-cooking plate.

In addition, in Patent Document 2, a through hole is provided in the center of the cooking plate to facilitate the drainage of meat juices or oil, and multiple ribs are provided above the through hole to bridge the hole. A downwardly protruding rib is formed around the through hole of the plate to prevent the backflow of meat juices. Patent Document 3 describes a zigzag cross-sectional irregularity called a heat supplement section. The irregularity is a triangular wave shape that increases and decreases in thickness around the average thickness of the cooking plate.

In Patent Document 4, the heating section (heater) is concentrated in the center of the plate, and the periphery is partially heat-shielded by the back groove, with the outer surface of the back groove serving as the heat-retaining section. Therefore, the position where the back groove is formed on the plate is set to 5 to 10 cm from the edge, since it necessarily requires a mounting space as a heat-retaining section.

In Patent Document 5, a groove with a semicircular cross section is formed on the back surface of the plate along the outer edge of the heater, which reduces heat loss to the surroundings, speeds up the temperature rise on the cooking surface, and increases the maximum temperature.

In Patent Document 6, a recess on the back surface is provided at the boundary between the cooking area and the flange in order to reduce heat loss to the outer periphery of the plate. Furthermore, a low thermal conductivity material such as stainless steel is fitted into the recess. The low thermal conductivity material is not a normal insulating material, but a low thermal conductivity metal, and by protruding from the underside of the plate, it doubles as a leg or trivet when the plate is lifted up and placed on a table. Incidentally, the thermal conductivity of still air and stainless steel (SUS304) are 0.0242 W/mK and 16.0 W/mK, respectively, so fitting the low thermal conductivity material (SUS304) does not suppress heat conduction.

In Patent Document 7, a temperature-regulating recess (a portion with a thin wall thickness) is provided at the end of the grill plate (cooking plate), with the aim of increasing the temperature of the end and expanding the cooking surface. The heating portion and the end of the temperature-regulating recess overlap in a cross-sectional view.

Patent Document 8 describes the provision of a thin-walled portion of thickness t to absorb thermal distortion during casting or use of an electric heating plate (cooking plate). In one example, a groove with a rectangular cross section is provided on the front and back of the plate, separated by a distance of thickness t. However, in order to form the thin-walled portion, multiple grooves are required on the front and back, and in order to absorb distortion, the thickness t must be less than the thickness of the plate.

JP 2021-083743 A JP 2011-218081 A Japanese Patent Application Publication No. 10-179411 Publication No. 8-35 Japanese Patent Application Publication No. 6-209864 Japanese Patent Application Publication No. 10-328036 JP 2012-214 A Japanese Utility Model Application Publication No. 52-145543

The objective of this invention is to provide a portion of reduced thickness at the rear end of the plate, thereby inhibiting heat conduction to the end of the plate, preventing a drop in temperature on the effective cooking surface on the front surface of the plate where cooking takes place, and suppressing heat loss due to dissipation outside the effective cooking surface of the plate.

The objective of the product is also to prevent overheating of the housing of the cooking appliance that comes into contact with the cooking plate, to facilitate compliance with the upper limit temperature regulated by public standards, to enable the use of inexpensive materials with good formability such as resins that have poor heat resistance, to prevent discoloration of stainless steels such as SUS304 that discolor when heated, to maintain a good appearance, and to partially prevent broth and oil from spreading from the edge of the plate to the back side.

In the present invention, the cooking plate of a cooking appliance in which food is placed on the surface of the plate and cooked from the backside or inside of the plate, a recess with a reduced thickness and a rectangular cross-sectional shape is provided on the outer edge of the backside of the effective cooking surface set on the surface of the plate, reducing the heat capacity and inhibiting heat conduction outside the effective cooking surface.

The amount of heat transferred by thermal diffusion in a solid, i.e., thermal conduction, is proportional to the cross-sectional area of the path and inversely proportional to the length. By providing a recess with a rectangular cross-sectional shape and reduced thickness at the back edge of the effective cooking surface of the plate, the cross-sectional area through which heat passes toward the edge of the plate is reduced in that area, so heat conduction from the center of the plate to the edge is inhibited and the amount of heat that reaches the edge outside the recess is proportionally reduced.

In addition, the broth or oil that has spread from the edge of the plate to the back side must move vertically up and down the concave portion of the back side, and the effect of gravity or the effect of the increased distance overcomes the surface tension, preventing the broth or oil from spreading.

By reducing the thickness of the plate in the recess from the back surface to a rectangular cross section, the thinnest part becomes flat, wider than recesses with other cross sections, and creates the longest distance for heat to travel, maximizing the effect of inhibiting heat conduction. Incidentally, if the thickness is reduced to a semicircular cross section, the thinnest part becomes a point. In the center, which is inside the recess, the amount of heat dissipated by thermal conduction decreases, so the temperature rises and the thermal function as an effective cooking surface increases.

When a cooking plate is heated from its backside with an electric sheath heater, lamp heater, or gas flame, a temperature distribution occurs across the cross section of the plate where the temperature is higher on the backside and decreases towards the front. In addition, heating is usually done in a planar manner in the center of the plate where cooking takes place, so a temperature distribution occurs on the plate surface where the center is hotter than the edges, and heat diffuses (thermally conducts) from the center of the plate to the edges.

However, due to the temperature distribution on the front and back as described above, the heat conduction from the back side where the temperature difference is greater is greater than that from the front side when it moves from the center to the edges, and the inhibition of heat transfer due to the cross-sectional area reduction effect caused by reducing the thickness is more effective when recesses are formed on the back side than on the front side. Note that when an electric resistance wire heater is cast inside the plate or when IH (induction heating) heating is used, internal heat is generated, so although the effect is less than when heating the back side, the effect of inhibiting heat transfer to the surroundings is still maintained.

The effective cooking surface is a flat plate, a perforated plate, or a plate with multiple depressions. The thickness of the back edge of the plate is reduced to form the effective cooking surface on the surface inside the depressions. The periphery of the effective cooking surface is kept flat, but the shape of the effective cooking surface may be modified depending on the type of cooking. For example, steak, okonomiyaki, pancakes, etc. are basically flat, but for yakiniku and seafood grilling, perforated plates with long holes (so-called rostre), shapes with multiple projections and recesses (ribs) of about several mm are used, or wire mesh is used, for Genghis Khan, etc., a helmet shape is used, and for baked goods such as takoyaki and imagawayaki, a plate with multiple depressions is used. Even if such a deformation is applied to the effective cooking surface, the same effect as a flat plate can be achieved by providing a portion with reduced thickness on the back side of the outer edge of the effective cooking surface.

The bottom edge of the outer periphery of the plate is located at the same height as the back surface of the effective cooking surface or lower than that back surface. In other words, the thickness of the outer periphery is increased so that the bottom edge of the outermost periphery of the entire plate is located at the same height as or lower than the bottom edge of the effective cooking surface. Methods for increasing the thickness include integral molding by casting or forging, and cutting grooves by machining.

In this configuration, the heat capacity and surface area of the outer periphery of the plate increases, lowering the temperature in that area. At the same time, the increased unevenness on the back surface more effectively prevents broth and oil from spreading to the back surface of the plate. In addition, when implementing this invention as a specification change, the shape of the outer periphery can be kept the same as before the thickness was reduced, so compatibility with conventional plates can be maintained.

The upper end of the outer periphery of the plate is made slightly higher than the effective cooking surface so that the oil and fat generated during cooking can be blocked. If the end of the plate is flat, the broth and oil may spread over the surface of the plate and some of it may flow to the back side. In order to prevent this, it is effective to make the plate end surface higher. On the other hand, making the end surface higher unnecessarily will increase costs. In some household hot plates, the plate end surface is called a flange and has a height of 50 mm or more, similar to a pot, so that simple hot pot dishes such as sukiyaki can also be made. However, if the cooking appliance does not handle soup cooking, a height that can block the oil and fat and meat juices associated with cooking is sufficient, and the height of the plate end is set slightly higher than the upper end of the effective cooking surface and is higher than the effective cooking surface by a dimension of 1.5 times or less of the thickness of the effective cooking surface. It is ideal that it is about 0.5 to 1.5 times higher than the thickness of the effective cooking surface. At this height, cooking utensils (chopsticks, spatulas, levers, knives, forks, tongs, etc.) will not come into contact with it and cooking operations will not be impeded. Furthermore, if there is grease or oil that exceeds this height and spreads to the back side, lowering the bottom edge of the outer periphery of the plate as described above will prevent it from spreading to the back side.

The present invention is based on the results of the inventor's development to expand on the effect of the discovery made during an experiment by the inventor that when grooves are cut from the back side near the end face of a plate for cooking, the high temperature part of the surface (cooking surface) spreads. The effects of reducing the thickness of the plate to have a rectangular cross section are as follows.
1. Energy saving effect by preventing heat from escaping (diffusion/dissipation) around the plate edge and reducing the amount of heat added. 2. Improved cooking function by increasing the temperature of the effective cooking surface due to heat loss from the plate edge and reduced heat capacity. 3. If the reduced thickness on the back of the plate is grooved, it can lower the temperature of the plate edge, making it easier to prevent overheating of components in contact with the plate (usually the housing) and comply with temperature regulations, or to convert contact components and secondary contact components to low heat resistant materials. 4. If the reduced thickness on the back of the plate is grooved, it can lower the temperature of the plate edge and reduce burns when inadvertently touching the plate edge or contact components (improved safety).

FIG. 1 is a schematic diagram of a cooking device using a cooking plate according to a first embodiment of the present invention; (a) is a front view of the plate, (b) is a back view of the plate, and (c) is a cross-sectional view of the plate. 1 is a cross-sectional view of a plate with an end cut out according to a second embodiment; 10 is a cross-sectional view of a plate having grooves formed on the surface of the third embodiment; 4 is a cross-sectional view of a plate containing insulation according to a fourth embodiment; 5 is a cross-sectional view of a perforated plate according to the fifth embodiment; FIG. 13 is a cross-sectional view of a plate having a recess according to the sixth embodiment; 13 is a cross-sectional view of a plate serving as a grill according to the seventh embodiment; 13 is a cross-sectional view of a plate provided with a damming member according to the eighth embodiment; FIG. 13 is a cross-sectional view of a stepped plate according to the ninth embodiment; FIG. 13 is a diagram showing a result of a non-steady state heat conduction simulation of a plate according to the first embodiment; A diagram showing the results of a transient heat conduction simulation of a plate with different recess sizes, etc. Figure showing the results of a transient heat conduction simulation of a plate with a cut-out at one end

A cooking appliance using the cooking plate of the first embodiment is shown in Figure 1. This cooking appliance is a gas griddle, in which a flat cooking plate 1 is placed on the appliance body 3 by legs 2 made of cap nuts. In the figure, 4 is a leg rubber, 5 is a gas appliance valve, 6 is an irregular joint clip, 7 is a base plate, 8 is a burner stand, 9 is an igniter, 10 is a damper, 11 is a gas connection port, 12 is a thermostat, 13 is a heat reflector, 14 is a gas burner, 15 is an oil can, 16 is a heat shield, and 17 is a burner frame plate.

As shown in FIG. 2, the plate 1 is a flat plate that is rectangular in plan view, and a recess 20 with a reduced thickness and a rectangular cross-sectional shape is provided at the end of the back surface of the plate 1, and an effective cooking surface is set on the surface of the plate 1 according to the recess 20. The recess 20 reduces the heat capacity outside the effective cooking surface and inhibits heat conduction outside the effective cooking surface. The effective cooking surface is the area on the surface of the plate 1 that becomes hot, and the food to be cooked is placed on the effective cooking surface.

The plate 1 is relatively thick, and is often about 4 mm to 30 mm thick. It can be made of metal such as steel, cast iron (including various iron alloys), stainless steel (SUS304, SUS430, etc.), copper (including copper alloys), or aluminum (including aluminum alloys). Alternatively, it can be made of non-metallic plates such as wire mesh, ceramic plates (including ceramic plates and crystallized glass plates), or stone plates. It can be manufactured by casting, forging, machining, etc., and assembled in part using welding or screws, etc. It can be used for cooking okonomiyaki, steak, yakiniku, takoyaki, Genghis Khan, baked goods, etc., and the shape of the effective cooking surface is made to match the finished shape of each dish.

A groove is formed around the entire circumference near the end of the back surface of the plate 1, and this groove is a recess 20 with a reduced thickness. The recess 20 is continuously provided along the four sides of the rectangular plate 1 in a rectangular shape in plan view. The recess 20 is formed in a rectangular cross section and is a space surrounded by a flat inner wall 20a, an outer wall 20b, and an upper wall 20c. When the recess 20 is formed by machining, a groove with a rectangular cross section is cut along the outer periphery of the plate 1 using an end mill on the back surface of the metal plate plate 1. The depth of the groove is, for example, 1/2 the thickness of the plate 1, but is not limited to this, and may be any depth that can ensure the strength of the plate 1 at a minimum. When forming by machining, it is preferable to give small radii (roundness) to the four corners of the rectangular groove in plan view from the perspective of safety or strength. When the plate 1 is made by casting, the groove is formed using a mold. In this case, the recess 20 is formed into a trapezoid close to a rectangle taking into account the draft angle. If the plate 1 is circular, the recess 20 is a circular groove that runs along the outer periphery of the plate 1.

The effective cooking surface is set in the center of the surface of the plate 1, which is an area inside the recess 20. Here, since legs 2 are provided at the four corners of the plate 1, the position of the recess 20 is inward from the outer periphery of the plate 1 by the attachment dimension of the legs 2. Here, the position of the inner wall 20a of the recess 20 is set within 40 mm from the outer periphery. Therefore, the outer edge of the effective cooking surface is located within 40 mm from the outer periphery of the plate 1.

In this way, by providing the recess 20 at the end of the back surface of the plate 1, heat conduction from the center to the end can be effectively inhibited, the temperature of the effective cooking surface inside the recess 20 can be increased, and the temperature at the end outside the recess 20 can be decreased, allowing cooking to be done at a high temperature on the effective cooking surface. Moreover, since food is not placed on the end of the plate 1, the recess 20 is provided as close to the outer periphery of the plate 1 as possible, allowing the effective cooking surface to be set wide.

The thickness of the plate 1 is at its thinnest in the recess 20, which has a rectangular cross section, and the outer surface of this thin section is flat, making it wider than grooves with other cross sections and providing the longest distance for heat to pass through. This maximizes the effect of inhibiting heat conduction.

As shown in FIG. 3, the second embodiment of the heating and cooking plate 1 has a recess 20 provided on the outer periphery of the back surface of the plate 1. The recess 20 is formed by cutting out a rectangular shape of a specified width from the outer edge of the back surface of the plate 1. Legs (not shown) are attached to the recess 20, and the plate 1 is supported in a position above the device body 3. This significantly impedes heat conduction to the device body 3. In addition, since the recess 20 does not overlap with the range of the heat source, heat loss to the end of the plate 1 is reduced accordingly. The other configurations are the same as those of the first embodiment.

As shown in FIG. 4, in the third embodiment of the cooking plate 1, anti-flow grooves 21 are formed along the four sides of the surface of the plate 1 so as to be located outside the recesses 20. The other configurations are the same as those of the first embodiment. The anti-flow grooves 21 prevent the broth and oils generated during cooking from flowing out to the outer periphery of the plate 1. The anti-flow grooves 21 have a rectangular cross section, and the distance between the inner wall 21a of the anti-flow grooves 21 and the outer wall 20b of the recesses 20 is approximately the thickness of the effective cooking surface. By providing the anti-flow grooves 21, a certain degree of heat conduction inhibition effect can be obtained, but by providing two grooves on the front and back, the heat path is bent and extended in a labyrinth shape, enhancing the heat conduction inhibition effect.

As shown in FIG. 5, the fourth embodiment of the cooking plate 1 has a heat insulating material 22 housed in the recess 20. The other configurations are the same as those of the first embodiment. Since the applicable temperature of the cooking plate 1 is high, an inorganic material is suitable for the heat insulating material 22, and examples of such materials include rock wool, perlite, and insulating brick materials. Heat dissipation occurs due to convection heat transfer from the surface of the groove forming the recess 20 to the surroundings, but by providing the heat insulating material 22, heat dissipation is suppressed, a drop in the temperature of the effective cooking surface can be prevented, and the energy saving effect can be maximized.

As shown in FIG. 6, the fifth embodiment of the cooking plate 1 is a flat plate with holes, a so-called rotisserie. The other configuration is the same as that of the first embodiment. On the effective cooking surface of the plate 1, multiple slits 23 are formed parallel to the short sides and are used as openings for separating and dropping broth and fats. At the same time, they also serve as a passageway for hot air heated by a heater or the like on the back side, and in the case of gas heating, they also serve as part of the exhaust passage. This allows food to be browned in stripes.

As shown in FIG. 7, the sixth embodiment of the heating and cooking plate 1 is a plate for takoyaki, with multiple hemispherical depressions 24 provided on the effective cooking surface. If these depressions 24 are shallow, with a diameter of about 100 mm, it becomes a plate for imagawayaki. The other configurations are the same as those of the first embodiment. Even in this type of plate 1, the outside of the effective cooking surface is flat, so by providing recesses 20 on the back surface, it is possible to inhibit heat conduction to the edge of the plate 1 and increase the temperature of the effective cooking surface.

As shown in FIG. 8, the seventh embodiment of the cooking plate 1 is a grill. The other configurations are the same as those of the first embodiment. The plate 1 is formed by combining horizontal wires 25 and vertical wires 25. The horizontal and vertical wires 25 located near the ends of the plate 1 are thinned to reduce the cross-sectional area, forming the recesses 20. For example, the wires 25 are drawn to reduce the cross-sectional area of the wires 25. The cross-section of the drawn wires 25 is usually circular, but if a special mold is used, it can be made semicircular or rectangular with a flat bottom surface. Alternatively, if the position to be drawn is press-molded, the wires 25 can be made to have a cross-sectional shape corresponding to the mold, thereby reducing the cross-sectional area. By providing recesses 20 at the ends of the mesh-like plate 1, it is possible to inhibit heat conduction to the ends of the plate 1.

As shown in FIG. 9, the eighth embodiment of the cooking plate 1 is provided with a damming member 26 on the outer periphery of the plate 1 of the second embodiment to prevent oil and grease and broth from flowing to the back side of the plate during cooking. The other configurations are the same as those of the first embodiment. The damming member 26 is a thin tape-shaped flat plate, for example, a steel strip several mm thick, attached to the outer periphery of the plate 1 by welding. The upper end of the damming member 26 is located higher than the effective cooking surface, and the lower end is located at the same height as or lower than the back side of the effective cooking surface and lower than the upper wall of the recess 20. The upper part of the damming member 26 prevents oil and grease from flowing to the back side of the plate 1, but if the oil and grease flows over the upper end of the damming member 26, the oil is drained at the lower part of the damming member 26 to drip off the oil and grease. Therefore, there is no need to make the upper end of the damming member 26 unnecessarily high; its height should be sufficient if it is about the thickness of the effective cooking surface.

As shown in FIG. 10, the ninth embodiment of the heating and cooking plate 1 has a step 27 at the end of the plate 1 that is higher than the effective cooking surface. The other configurations are the same as those of the first embodiment. The step 27 is formed from the outer edge of the effective cooking surface to the outer peripheral surface of the plate 1, the height of the step 27 is less than the thickness of the effective cooking surface, and the inner wall 27a of the step 27 is closer to the center than the inner wall 20a of the recess 20. The outer edge of the effective cooking surface is located at the position of the inner wall 27a of the step 27. The depth of the groove that forms the recess 20 is increased, and the thickness of the plate 1 at the recess 20 is not increased.

Providing such a step 27 can prevent grease from seeping around to the back surface of the plate 1. In addition, as the thickness of the end of the plate 1 increases, the heat capacity also increases, so the temperature rise in that area is also suppressed.

The temperature change in the cross section of the plate when the thickness of the cooking plate 1 near the rear end portion is reduced was confirmed by using a numerical calculation. The calculation was carried out by solving the unsteady two-dimensional heat conduction equation (1) by the implicit finite difference equation (2).

Examples of boundary conditions are given in the table below. The symbols are based on general notation in the heat transfer field, but are roughly as follows:
Symbols: T (absolute) temperature, x, y (horizontal and vertical (thickness) coordinates), t (time), α (thermal diffusivity), Qv (heat release rate), λ (thermal conductivity), ρ (density), c (specific heat), h (heat transfer coefficient), qw (external heat quantity), subscripts: i, j (position number in x and y directions), k (time number), f (temperature boundary layer), w (wall surface)

Since the calculation was performed in two dimensions, the calculated temperature distribution corresponds to that of the central cross section of the plate 1, which has a width of 200 mm and an infinite depth (effectively 3 to 5 times the width or more). The calculation was performed for each 1 mm of width and thickness (1 mm mesh), and the time was 5 seconds. Heating was performed in a 100 mm wide range on the back surface of the central part of the plate 1, with a heat quantity of 9.375 kW/m ² for a 6 mm thick iron plate and 18.75 kW/m ² for a 12 mm thick iron plate. The heat transfer coefficient from the plate 1 to the surrounding environment was set to 20 W/m ² except for the non-heated back surface part, which was set to 0 W/m ² (insulated). This is because the non-heated back surface part is located around the heating part, and the temperature inside the cooking appliance in that part rises, and it was thought that there was no heat loss or rather that it was in the direction of heat reception. The calculation was deemed to have converged when the difference between the current and previous calculated temperatures at each position on the cross section became less than 0.000001° C. at all grid points.

The five tables listed in FIG. 11 show the results of calculations of the unsteady temperature distribution in the central cross section of plate 1 after 60 seconds (1 minute), 120 seconds (2 minutes), 180 seconds (3 minutes), 300 seconds (5 minutes), and 600 seconds (10 minutes) from the top after heating. The calculations were performed using the physical properties of a mild steel plate with a width of 200 mm and a thickness of 6 mm. The values in each cell represent the temperature in degrees Celsius at a depth of j mm from the surface of plate 1 and a distance of im mm from the left end, but the portion 10 mm from the left end, which corresponds to the portion where the thickness was reduced (recess 20), has a width of 30 mm and a depth of 4 mm and is left blank. The calculation of the thickness reduction was performed only on the left half surface, not on the right half surface. Therefore, the effect of the thickness reduction can be seen by comparing the values of the cells at symmetrical positions on the left and right sides. The values in the first and second columns of the table represent the depth of j mm from the surface, and the values in the first and second rows represent the distance im mm from the left end. Therefore, each cell from the third column and third row in the table represents the temperature of that portion. Incidentally, the value at the position where j is 0 mm, i.e., a depth of 0 mm, corresponds to the surface temperature of plate 1, and the value at the position where i is 0 mm represents the surface temperature at the left end. Similarly, the position where j is 6 mm represents the surface temperature of the back surface, and the position where i is 200 mm represents the surface temperature at the right end. Comparing the temperatures at symmetrical positions near the ends of plate 1, we can see that the temperature is higher near the center of the part where the thickness has been reduced than at the symmetrical position, and lower near the left end than at the symmetrical position.

Figure 12 compares the calculation results after 300 seconds when the thickness of plate 1 is reduced by changing its size, total thickness, adding insulation, or changing the material (using physical properties equivalent to SUS304). The left edge of the part with reduced thickness (recess 20) is 10 mm from the left edge of plate 1. 12-1 is made of mild steel, has a thickness of 6 mm, a groove width of 20 mm, and a depth of 4 mm; 12-2 is made of mild steel, has a thickness of 6 mm, a groove width of 30 mm, and a depth of 3 mm; 12-3 is made of mild steel, has a thickness of 6 mm, a groove width of 30 mm, and a depth of 4 mm; 12-4 is made of mild steel, has a thickness of 12 mm, a groove width of 30 mm, and a depth of 8 mm; 12-5 is made of mild steel, has a thickness of 6 mm, the groove is filled with insulating material, has a groove width of 30 mm, and a depth of 4 mm; and 12-6 is made of stainless steel (SUS304), has a thickness of 6 mm, a groove width of 30 mm, and a depth of 4 mm. In all cases, it can be seen that the temperature is higher near the center of the reduced thickness than at the symmetrical position, and lower near the left end than at the symmetrical position. This confirms that the four effects listed under Effects of the Invention have been achieved.

Figure 13 shows the calculation results after 300 seconds when the thickness of the back surface of the end of plate 1 as shown in Figure 3 was reduced (cut out). 13-1 is made of mild steel, with a groove width of 20 mm and depth of 6 mm, 13-2 is the same as 13-1, but with the groove width changed to 30 mm, 13-3 is the same as 13-2, but with the groove insulated, and 13-4 is the same as 13-2, but with the material changed to stainless steel (SUS304). It can be seen that regardless of the size of the cutout at the end, the insulation, or the change in material, the temperature is higher above the part where the thickness has been reduced or near the center than at a symmetrical position. In this case, it can be seen that the effect of improving cooking function, one of the effects listed under the effects of the invention, has been achieved. Furthermore, legs 2 are usually attached to the cut-out portions with bolts or the like to restore the height, preventing heat from escaping (diffusing or dissipating) from the ends of plate 1 through legs 2 to the surroundings. This reduces the amount of heat applied, resulting in energy savings. By providing a portion with reduced thickness at the end of plate 1 and using legs 2, it is possible to easily make contacting parts (often the housing) comply with temperature regulations, or to convert contacting parts and secondary contacting parts to low heat-resistant materials.

The present invention is not limited to the above embodiment, and it is of course possible to make many modifications and changes to the above embodiment within the scope of the present invention. Among the cooking plates 1, the rosters and Genghis Khan pots often have grooves on the surface to separate and store broth and oils. The grooves can be provided on the outside (end side) or inside (center side) of the surface portion corresponding to the recess 20 on the back surface. In particular, if provided on the outside, the heat transfer inhibition effect of the recess 20 on the back surface suppresses evaporation of broth and oils in the grooves on the surface. Conversely, if provided on the inside, evaporation is promoted. Which is more appropriate can be determined based on the cooking purpose and the effort required for cleaning.

Casting is a simple and inexpensive way to create grooves for the recesses 20 on the edge of the plate 1. In particular, it is reasonable to mold the so-called rostre, which has many long holes on the cooking surface, and the plate 1, which has openings and irregularities on the cooking surface, such as the plate 1 for takoyaki or the Genghis Khan pot, by casting. As for casting methods, it is possible to use not only general sand casting (normal casting), but also lost wax casting, which is used for more precise shaping, and die casting, which is used for low-melting-point metals such as aluminum.

The recesses 20 in the plate 1, whose effective cooking surface is flat, are best formed by machining using an end mill. At the same time, machining the parts that are visible on the outside can also be used to create a high-quality finish.

Since the plate 1 is formed to be relatively thick overall (4 mm or more), hot forging is appropriate for manufacturing it by forging. Plate 1 that has been appropriately heat-treated after forming has the advantage that it is less susceptible to thermal deformation (warping and twisting) when heated during cooking.

REFERENCE SIGNS LIST 1 plate 2 leg 3 device body 20 recess 21 outflow prevention groove 22 heat insulating material 23 slit 24 depression 25 wire rod 26 damming member 27 step

Claims (3)

This cooking plate for a cooking appliance in which ingredients are placed on the surface of the plate and heated from the back or inside of the plate to cook the ingredients is characterized in that the end of the back surface of the plate has a recess with a rectangular cross-sectional shape that reduces the thickness, an effective cooking surface for cooking at high temperatures is set on the surface of the plate inside the inner wall of the recess, and a groove is provided on the surface of the plate outside the recess to store broth and oil generated during cooking and prevent it from flowing out to the outer periphery of the plate, and the recess inhibits heat conduction outside the effective cooking surface. A cooking plate for a cooking appliance in which ingredients are placed on the surface of the plate and heated from the back or inside of the plate to cook them, the cooking plate having a recess with a rectangular cross-sectional shape of reduced thickness at the end of the back of the plate, an effective cooking surface for cooking at high temperatures is set on the surface of the plate inside the recess, a step higher than the effective cooking surface is formed at the end of the front surface of the plate from the outer edge of the effective cooking surface to the outer periphery of the plate to prevent broth and oils generated during cooking from flowing around to the back of the plate, the inner wall of the step which forms the outer edge of the effective cooking surface is closer to the center than the inner wall of the recess, and the recess inhibits heat conduction outside the effective cooking surface. 3. The cooking plate according to claim 1, further comprising legs provided on the rear surface of the plate outside the recess.

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