JP7783285B2 - heating device - Google Patents

Description

The disclosed embodiments relate to a heating device.

Patent document 1 discloses a heating device that includes a plate-shaped mold with a hole extending in the thickness direction in the center of the heating surface and multiple horizontal holes on the side to avoid the hole, and multiple heaters inserted into each of the horizontal holes.

Japanese Patent Application Laid-Open No. 2019-11224

A heating device according to one embodiment includes a heating plate and multiple heaters. The heating plate has a heating surface and a back surface opposite the heating surface. The heating plate has a hole extending in the thickness direction at the center of the heating surface, and multiple recesses formed around at least the area of the back surface corresponding to the hole. The multiple heaters are inserted into the multiple recesses, respectively.

FIG. 1 is a side view of a heating device according to an embodiment. FIG. 2 is a top view of the heating device according to the embodiment. FIG. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is a cross-sectional view of a heating device according to a first modified example of the embodiment. FIG. 5 is a cross-sectional view of a heating device according to a second modification of the embodiment. FIG. 6 is a cross-sectional view of a heating device according to a third modification of the embodiment. FIG. 7 is a cross-sectional view of a heating device according to a fourth modification of the embodiment. FIG. 8 is a top view of a heating device according to a fifth modification of the embodiment.

Embodiments of the heating device disclosed herein will be described below with reference to the accompanying drawings. Note that the present disclosure is not limited to the embodiments shown below. It should be noted that the drawings are schematic, and the dimensional relationships and ratios of each element may differ from reality. Furthermore, there may be parts in which the dimensional relationships and ratios differ between the drawings.

In addition, in the embodiments described below, expressions such as "constant," "orthogonal," "perpendicular," or "parallel" may be used, but these expressions do not necessarily mean "constant," "orthogonal," "perpendicular," or "parallel" in the strict sense. In other words, the above expressions allow for deviations due to, for example, manufacturing precision, installation precision, etc.

<Embodiment>
Fig. 1 is a side view of the heating device 100 according to the embodiment. Fig. 2 is a top view of the heating device 100 according to the embodiment. In the following description, when the heating device 100 is brought into contact with the object to be heated, the surface facing the object to be heated is referred to as the "upper surface," and the surface facing the opposite side to the object to be heated is referred to as the "lower surface." However, the heating device 100 may be used, for example, upside down, or in any position.

As shown in FIG. 1, the heating device 100 has a heating plate 110, multiple heaters 120, and a fixed plate 130.

The heating plate 110 is, for example, a metal plate-shaped member, and has an upper surface 110a that can come into contact with the object to be heated. In other words, the upper surface 110a of the heating plate 110 serves as the heating surface (an example of a first surface) that heats the object to be heated. The upper surface 110a is used, for example, to heat a mold, which is an example of the object to be heated. A plurality of recesses 113 are formed on the lower surface (an example of a second surface) 110b of the heating plate 110, which is on the opposite side to the heating surface (see Figure 3).

The heaters 120 are, for example, ceramic heaters having a ceramic body and a heating resistor located inside the ceramic body. By using ceramic heaters as the heaters 120, it is possible to reduce seizure between the metal heating plate 110 and the heaters 120.

The length of the heater 120, i.e., the length of the ceramic body, can be, for example, approximately 1 mm to 200 mm. The outer dimensions of the ceramic body can be, for example, approximately 0.5 mm to 100 mm. The shape of the heater 120, i.e., the shape of the ceramic body, is not limited to a cylindrical shape, but can also be, for example, an elliptical cylinder or a rectangular column. The ceramic body is made of, for example, an insulating ceramic. Examples of ceramic body materials that can be used include oxide ceramics, nitride ceramics, and carbide ceramics. The heating resistor is a component that generates heat when an electric current flows through it. The heating resistor may include, for example, a high-resistance conductor containing tungsten, molybdenum, or the like. The dimensions of the heating resistor can be, for example, a width of 0.1 mm to 5 mm, a thickness of 0.05 mm to 0.3 mm, and a total length of 1 mm to 500 mm. The heating resistor may also be made of, for example, a conductive ceramic containing tungsten carbide. In this case, the thermal expansion difference between the ceramic body and the heating resistor can be reduced. This reduces the thermal stress between the ceramic body and the heating resistor, thereby improving the durability of the heater 120.

The heaters 120 are positioned in each of the recesses 113 in the heating plate 110. That is, by inserting the heaters 120 into the recesses 113, they are positioned perpendicular to the upper surface 110a of the heating plate 110, which is the heating surface.

In this way, by arranging the multiple heaters 120 perpendicular to the heating surface of the heating plate 110, it is possible to reduce the variation in the distance between the multiple heaters 120 and the heating surface. As a result, it is possible to improve the temperature uniformity within the upper surface 110a of the heating plate 110, which is the heating surface.

The fixed plate 130 is, for example, a plate-shaped member made of metal. Multiple heaters 120 are fixed to the fixed plate 130.

Next, the heating plate 110, the multiple heaters 120, and the fixing plate 130 will be described in more detail with reference to Figures 2 and 3. Figure 3 is a cross-sectional view taken along line III-III in Figure 2. Note that Figure 2 shows a planar perspective view of the heating plate 110 as seen from a direction perpendicular to the upper surface 110a. As shown in Figures 2 and 3, the heating device 100 is configured such that the multiple heaters 120 are fixed to the fixing plate 130 and inserted into the multiple recesses 113 of the heating plate 110.

The heating plate 110 has an upper surface 110a and a lower surface 110b. The upper surface 110a is the heating surface that heats the object to be heated, and the lower surface 110b is the reverse side of the heating surface.

As shown in Figures 2 and 3, a hole 116 extending in the thickness direction of the heating plate 110 is formed in the center of the upper surface 110a. The hole 116 extends in the thickness direction of the heating plate 110 to a depth that does not penetrate the heating plate 110 from the upper surface 110a to the lower surface 110b. For example, the hole 116 extends to a position that reaches the insulating member 115, described below, that the heating plate 110 has. The cross-sectional shape of the hole 116 may be any shape. For example, the hole 116 shown in Figure 3 has a cross-sectional shape with straight sides. The diameter (width) of the hole 116 may be any diameter. For example, the hole 116 shown in Figure 3 has a smaller diameter than each of the multiple recesses 113.

By forming a hole 116 in the center of the upper surface 110a of the heating plate 110, which is the heating surface, heat at the center of the upper surface 110a can be released into the atmosphere within the hole 116. In other words, heat is less likely to escape from the center of the upper surface 110a into the atmosphere surrounding the heating plate 110 than from the periphery of the upper surface 110a. For this reason, the temperature at the center of the upper surface 110a of the heating plate 110 may be higher than at the periphery. In contrast, by forming a hole 116 in the center of the upper surface 110a, heat at the center of the upper surface 110a can be released into the atmosphere within the hole 116, thereby increasing the amount of heat dissipation at the center of the upper surface 110a compared to the amount of heat dissipation at the periphery of the upper surface 110a. This reduces the temperature difference between the center and periphery of the upper surface 110a.

A plurality of recesses 113 into which the plurality of heaters 120 are inserted are formed around at least the area of the lower surface 110b corresponding to the hole 116. Specifically, the plurality of recesses 113 are formed at equal intervals along the periphery of at least the area of the lower surface 110b corresponding to the hole 116. In this embodiment, the plurality of recesses 113 are formed in a grid pattern at equal intervals over the entire surface of the lower surface 110b.

In this way, by forming multiple recesses 113 at equal intervals along the periphery of at least the region of the lower surface 110b corresponding to the hole 116, multiple heaters 120 can be evenly arranged around the periphery of the hole 116 on the upper surface 110a. In other words, the multiple heaters 120 are positioned around the hole 116 in a planar perspective (see Figure 2). This allows the multiple heaters 120 to evenly heat the region around the hole 116 without causing a temperature difference around the hole 116 on the upper surface 110a of the heating plate 110. As a result, the heating device 100 according to this embodiment can improve thermal uniformity around the hole 116 on the upper surface 110a, which is the heating surface.

The positions at which the recesses 113 are formed are not limited to those shown in Figure 2. For example, the recesses 113 may be formed concentrically across the entire surface of the lower surface 110b, with the area corresponding to the hole 116 at its center.

In addition, the heating plate 110 has a laminated structure in which a first plate member 111, a second plate member 112, and an insulating member 115 are stacked.

The first plate member 111 is a plate-shaped member having an upper surface 110a of the heating plate 110, which is the heating surface. The first plate member 111 is joined to the second plate member 112 by joining members 114, such as bolts, with an insulating member 115 disposed between the first plate member 111 and the second plate member 112. In other words, the lower surface 111a of the first plate member 111, opposite the upper surface 110a, is the joining surface that is joined to the second plate member 112. A cylindrical spacer member 170, made of, for example, highly insulating ceramic, is provided on the outer periphery of the joining member 114. A plurality of recesses 111b are formed on the lower surface 111a of the first plate member 111, opposite the heating surface.

The second plate member 112 is a plate-like member having an upper surface 112a, which serves as the joining surface to be joined to the joining surface of the first plate member 111, and a lower surface 110b located on the opposite side of the upper surface 112a. A plurality of through holes 112b are formed at positions corresponding to the plurality of recesses 111b of the second plate member 112.

The insulating member 115 is located between the first plate member 111 and the second plate member 112. That is, the insulating member 115 is interposed between the first plate member 111 and the second plate member 112. The insulating member 115 is, for example, a sheet-like member made of insulating fibers, and has the function of limiting the transfer of heat from the first plate member 111 to the second plate member 112. A plurality of through holes 115a are formed in the insulating member 115 at positions corresponding to the plurality of recesses 111b.

The material of the insulating member 115 is preferably, for example, ceramics with insulating properties. Examples of materials that can be used for the insulating member 115 include oxide ceramics, nitride ceramics, and carbide ceramics.

Each of the multiple recesses 113 is formed by a respective one of the multiple through holes 112b, a respective one of the multiple through holes 115a, and a plurality of recesses 111b. That is, the inner surfaces of each through hole 112b, each through hole 115a, and each recess 111b form the inner surface of each recess 113, and the bottom surface of each recess 111b forms the bottom surface of each recess 113. Furthermore, with the multiple heaters 120 inserted into the multiple recesses 113, the tips 120a of the multiple heaters 120 are positioned within the multiple recesses 111b.

The fixing plate 130 has multiple fixing holes 130a at positions corresponding to the multiple recesses 113. Multiple heaters 120 are inserted and fixed into the multiple fixing holes 130a. Specifically, an internal thread is formed on part of the inner wall of each fixing hole 130a. Meanwhile, a cylindrical mounting member 121 is attached to the outer surface of each heater 120, and an external thread 121a is formed on part of the outer surface of the mounting member 121. When each heater 120 is inserted into each fixing hole 130a, the external thread 121a engages with the internal thread of each fixing hole 130a, thereby fixing the multiple heaters 120 to the fixing plate 130.

The fixing plate 130 is positioned at a distance from the heating plate 110. As shown in Figures 2 and 3, the fixing plate 130 is connected to the heating plate 110 (second plate member 112) by connecting members 131, such as bolts, with a gap formed between the fixing plate 130 and the heating plate 110. By separating the fixing plate 130 from the heating plate 110 in this manner, it is possible to reduce the temperature rise in the fixed portions of the multiple heaters 120 relative to the fixing plate 130 (e.g., the portions where the mounting members 121 are attached). On the other hand, since the heat removed from the heating plate 110 by the fixing plate 130 is reduced, it is possible to promote the temperature rise of the heating plate 110.

A spacer member 140 is also disposed between the heating plate 110 and the fixed plate 130. The spacer member 140 is cylindrical and surrounds the portion of the connecting member 131 located between the heating plate 110 and the fixed plate 130, with both ends in contact with the heating plate 110 and the fixed plate 130. By providing the spacer member 140 between the heating plate 110 and the fixed plate 130, the possibility of collision between the fixed plate 130 and the heating plate 110 can be reduced.

The spacer member 140 can be made of a metal such as stainless steel. This improves the durability of the spacer member 140 and allows the distance between the fixed plate 130 and the heating plate 110 to be maintained constant.

The material of the spacer member 140 may be, for example, a heat-resistant ceramic. Materials that can be used for the spacer member 140 include, for example, oxide ceramics, nitride ceramics, and carbide ceramics. This reduces the thermal expansion and contraction of the spacer member 140, thereby reducing wear on the spacer member 140.

The heaters 120 have base ends 120b located farther from the upper surface 110a of the heating plate 110 (the heating surface) than the lower surface of the fixing plate 130 opposite the heating plate 110. Power supply terminals 122, 123 that supply power to the heaters 120 are provided at the base ends 120b. In other words, the base ends 120b of the heaters 120 protrude away from the upper surface 110a of the heating plate 110 (the heating surface) than the lower surface of the fixing plate 130, and the power supply terminals 122, 123 are provided at these base ends 120b. By providing the power supply terminals 122, 123 at the base ends 120b that protrude away from the upper surface 110a of the heating plate 110 (the heating surface), the power supply terminals 122, 123 can be spaced farther from the heating surface. As a result, the power supply terminals 122, 123 can be protected from the heat of the heating surface.

<Modification of the embodiment>
Next, various modified examples of the embodiment will be described with reference to Figures 4 to 8. In the following description, the same reference numerals will be used to designate components common to the above-described embodiment, and detailed description thereof will be omitted.

Figure 4 is a cross-sectional view of a heating device 100 according to a first variant of the embodiment. The heating device 100 shown in Figure 4 differs from the heating device 100 shown in Figures 1 to 3 mainly in the shape of the hole 116. Specifically, in the heating device 100 shown in Figure 4, the hole 116 has a cross-sectional shape in which the diameter (width) on the upper surface 110a side, which is the heating surface, is smaller than the diameter on the lower surface 110b side, which is the reverse side of the heating surface. In this embodiment, the hole 116 has a cross-sectional shape in which the diameter on the upper surface 110a side is smaller than the diameter on the lower surface 110b side and the side surface is stepped.

In this way, by making the diameter of the cross-sectional shape of the hole 116 on the upper surface 110a side smaller than the diameter on the lower surface 110b side, it is possible to reduce the decrease in strength of the upper surface 110a side of the heating plate 110. In other words, as the diameter of the hole 116 increases, the amount of heat dissipated from the center of the upper surface 110a to the atmosphere within the hole 116 can be increased, but on the other hand, this may result in a decrease in the strength of the upper surface 110a side of the heating plate 110. Because the upper surface 110a, which is the heating surface, is subjected to external forces from the heated object when it comes into contact with the heated object, a decrease in strength of the upper surface 110a side of the heating plate 110 can reduce the durability of the heating plate 110. In contrast, by making the diameter of the cross-sectional shape of the hole 116 on the upper surface 110a side smaller than the diameter on the lower surface 110b side, it is possible to relatively increase the strength of the upper surface 110a side of the heating plate 110. This reduces the decrease in strength of the upper surface 110a side of the heating plate 110, thereby improving the durability of the heating plate 110.

The cross-sectional shape of the hole 116 may be various shapes as long as the diameter on the upper surface 110a side is smaller than the diameter on the lower surface 110b side. For example, the hole 116 may have a cross-sectional shape in which the diameter on the upper surface 110a side is smaller than the diameter on the lower surface 110b side and the side surfaces are tapered or curved.

Figure 5 is a cross-sectional view of a heating device 100 relating to a second variant of the embodiment. The heating device 100 shown in Figure 5 differs from the heating device 100 shown in Figures 1 to 3 mainly in the diameter of the hole 116. Specifically, in the heating device 100 shown in Figure 5, the hole 116 has a larger diameter than each of the multiple recesses 113.

In this way, by making the diameter of the hole 116 larger than the diameter of each of the multiple recesses 113, the surface area and cross-sectional area of the hole 116 are increased, promoting heat dissipation to the atmosphere within the hole 116 and further improving thermal uniformity around the hole 116 on the upper surface 110a.

Figure 6 is a cross-sectional view of a heating device 100 relating to a third variant of the embodiment. The heating device 100 shown in Figure 6 differs from the heating device 100 shown in Figure 5 mainly in that the hole 116 penetrates the heating plate 110 to the underside 110b, which is the surface opposite the heating surface, and in that a cover member 180 is disposed within the hole 116. Specifically, in the heating device 100 shown in Figure 6, the hole 116 penetrates the first plate member 111, the insulating member 115, and the second plate member 112 that constitute the heating plate 110 to the underside 110b.

The hole portion 116 includes a first through hole 116a that penetrates the first plate member 111 and a second through hole 116b that penetrates the second plate member 112. The first through hole 116a and the second through hole 116b have approximately the same diameter. The exposed surface 115b of the insulating member 115, which is exposed between the first through hole 116a and the second through hole 116b, is recessed outward from the inner surfaces of the first through hole 116a and the second through hole 116b, forming a step between the first through hole 116a and the second through hole 116b. An annular cover member 180 is positioned in the step between the first through hole 116a and the second through hole 116b. The cover member 180 covers the exposed surface 115b of the insulating member 115. The cover member 180 may be made of a material such as ceramic or metal that has high heat resistance.

That is, the heating plate 110 may have an annular cover member 180 within the hole 116. The cover member 180 may cover the exposed surface 115b of the insulating member 115. This can reduce deterioration of the insulating member 115.

In this way, by having the hole 116 penetrate the heating plate 110 to the lower surface 110b, the surface area and cross-sectional area of the hole 116 are increased, promoting heat dissipation to the atmosphere within the hole 116 and further improving thermal uniformity around the hole 116 on the upper surface 110a.

In addition, by covering the exposed surface 115b of the insulating member 115 that is exposed within the hole 116 with the cover member 180, it is possible to reduce the adhesion of dust in the atmosphere within the hole 116 to the insulating member 115. This reduces deterioration of the insulating member 115.

Figure 7 is a cross-sectional view of a heating device 100 relating to a fourth variant of the embodiment. The heating device 100 shown in Figure 7 differs from the heating device 100 shown in Figure 6 in the arrangement of the cover member 180. Specifically, in the heating device 100 shown in Figure 7, the cover member 180 is fitted into a groove portion 111c formed in the lower surface 111a of the first plate member 111 with a gap between the cover member 180 and the inner surface of the groove portion 111c. The cover member 180 is not joined to the inner surface of the groove portion 111c with a bonding material. In other words, lateral movement of the cover member 180 within the groove portion 111c is not restricted.

In this way, the cover member 180 is fitted into the groove portion 111c of the first plate member 111 with a gap, thereby preventing the cover member 180 from falling off while allowing the cover member 180 to move laterally.

That is, the cover member 180 may be fitted into a groove 111c formed on at least one of the surface of the first plate member 111 opposite the first surface and the surface of the second plate member opposite the second surface, with a gap between the cover member 180 and the inner surface of the groove 111c. This prevents the cover member 180 from falling off while allowing lateral movement of the cover member 180.

In addition, by not joining the cover member 180 to the inner surface of the groove portion 111c, stress concentration on the cover member 180 due to thermal expansion and thermal contraction of the first plate member 111 can be alleviated.

The cover member 180 may be fitted into a groove formed on the upper surface 112a of the second plate member 112 with a gap between it and the inner surface of the groove. The cover member 180 may also be fitted into a groove formed on both the lower surface 111a of the first plate member 111 and the upper surface 112a of the second plate member 112 with a gap between it and the inner surface of the groove.

Figure 8 is a top view of a heating device 100 relating to a fifth variation of the embodiment. The heating device 100 shown in Figure 8 differs from the heating device 100 shown in Figures 1 to 3 in that other holes, different from hole 116, are formed in the upper surface 110a of the heating plate 110, which is the heating surface. Specifically, a plurality of other holes 117 (four in this example) extending in the thickness direction are formed in positions different from hole 116 on the upper surface 110a of the heating plate 110 shown in Figure 8. The positions at which the multiple other holes 117 are formed may be any positions. For example, the multiple other holes 117 may be formed at equal intervals along the outer periphery of hole 116 on the upper surface 110a.

In this way, by forming multiple other hole portions 117 at positions different from hole portion 116 on the upper surface 110a of the heating plate 110, distortion due to thermal expansion and thermal contraction of the heating plate 110 can be absorbed by the multiple other hole portions 117.

Further advantages and modifications may readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

100 Heating device 110 Heating plate 110a Upper surface 110b Lower surface 111 First plate member 111a Lower surface 111b Recess 111c Groove portion 112 Second plate member 112a Upper surface 112b Through hole 113 Recess 114 Joining member 115 Heat insulating member 115a Through hole 115b Exposed surface 116 Hole portion 116a First through hole 116b Second through hole 117 Hole portion 120 Heater 120a Tip 120b Base end 121 Mounting member 121a Male threads 122, 123 Power supply terminal 130 Fixing plate 130a Fixing hole 131 Connecting member 140 Spacer member 170 Spacer member 180 Cover member

Claims (6)

A heating plate;
a plurality of heaters;
the heating plate has a first surface and a second surface opposite the first surface;
The first surface has a hole in the center thereof,
the second surface has a plurality of recesses;
the plurality of heaters are inserted into the plurality of recesses in the heating plate, respectively, and are positioned around the hole in a plan view;
The heating plate is
a first plate member having the first surface;
a second plate member having the second surface;
a heat insulating member located between the first plate member and the second plate member;
and
the hole penetrates the first plate member, the heat insulating member, and the second plate member;
the heating plate has an annular cover member in the hole,
The cover member covers the exposed surface of the heat insulating member . The heating device described in claim 1, wherein the diameter of the hole on the first surface side is smaller than the diameter on the second surface side. The heating device described in claim 1 or 2, wherein the hole has a diameter larger than each of the plurality of recesses. 2. The heating device of claim 1, wherein the cover member is fitted into a groove formed on at least one of a surface of the first plate member opposite the first surface and a surface of the second plate member opposite the second surface, with a gap between the cover member and an inner surface of the groove. The heating device according to claim 4 , wherein the cover member is not bonded to the inner surface of the groove portion with a bonding material. The heating device described in claim 1, wherein the heating plate has a plurality of other holes at positions different from the positions of the holes on the first surface.