Heating apparatus and method

Abstract

When an object to be heated is heated without temperature nonuniformity in its heated surface, unwanted thermal deformation can be suppressed, and thermal processing precision can be improved. For this purpose, a heat transfer plate for heating a plate-like object to be heated, and a base plate are stacked. A rod heater as a heat source is inserted in the heat transfer plate. The heat transfer plate has a larger thermal conductivity and smaller creep than the base plate.

Description

BACKGROUND OF THE INVENTION[0001] The present invention relates to a heating apparatus and method and, more particularly, to a technique for supporting an object to be heated such as a glass plate and subjecting it to a uniform temperature process in order to uniformly heat it.[0002] Conventionally, in a heating apparatus for uniformly heating an object to be heated, as shown in FIG. 37, a plurality of cartridge type rod heaters 213 are inserted in a plate 212 made of one material. Outputs from the rod heaters 213 are controlled by a controller 214 by referring to a temperature obtained by at least one temperature sensor (not shown) provided to the plate 212, thereby heating an object 1 to be heated. To decrease in-plane temperature nonuniformity of a heating surface 212a of the plate 212, a material such as an aluminum alloy having a large thermal conductivity is used. To prevent deformation of the plate 212, a material such as stainless steel having a small thermal conductivity an...

AI Technical Summary

Benefits of technology

[0013] Along with a further increase in area of the plate of the heating apparatus, it has become necessary to enable free selection of the portion (region) to be heated by each heater and to perform temperature control of each heater separately, thereby reducing temperature distribution. For example, the temperature of the periphery of the plate decreases due to heat dissipation from the side surface. When outputs from heaters provided to the periphery of the plate are separately controlled to uniform the temperature, temperature distribution can be reduced. In the prior art, however, since the heaters are inserted in one direction of the plate, the thickness of the plate of the heating apparatus must be increased to prevent interference between the heaters in two directions, and the heaters must be set at different heights. As a result, the weight of the plate increases to increase its heat capacity, leading to an increase in power consumption and heating and cooling times. To enable a further plate area increase, temperature uniformity, and a small heat capacity, the heaters must be arranged at desired regions without increasing the plate thickness.

[0023] The present invention has been made in view of the problems described above, and has as its object to provide a heating apparatus that can realize a large area in order to improve the thermal processing precision of the object to be heated without increasing the weight and heat capacity per unit area of the heating plate.

[0025] It is still another object of the present invention to provide a heating apparatus in which heaters are located at desired regions so, even if the area of the plate is further increased, any temperature distribution can be reduced.

[0033] With the above arrangement, the first plate having a larger thermal conductivity than the second plate and the second plate having smaller creep than the first plate are stacked, so that any warp of the first plate resulting from heat of the heaters is suppressed by the second plate having smaller creep, and the object to be heated is heated by the first plate having a larger thermal conductivity without producing temperature nonuniformity in its heated surface. As compared to a heating apparatus using only the second plate having a smaller thermal conductivity, since the first plate having a larger thermal conductivity is used, the apparent heat capacity decreases, and the preheat time until the start of the thermal process can be shortened.

Problems solved by technology

As for the hole depth, increasing the depth while maintaining the same diameter as that of the prior art is technically difficult, and highly precise hole formation is limited in depth.

If the hole diameter is increased, while the processability increases and a deep hole can be formed easily, the plate thickness increases and the weight and heat capacity increase, leading to an increase in power consumption and heating and cooling times. For the heater, a length with which the heater can be fabricated with good precision for a certain diameter is limited.

In other words, an issue of realizing a large plate area without increasing the heat capacity per unit area of the plate arises.

As a result, the weight of the plate increases to increase its heat capacity, leading to an increase in power consumption and heating and cooling times. To enable a further plate area increase, temperature uniformity, and a small heat capacity, the heaters must be arranged at desired regions without increasing the plate thickness.

As a result, uniforming the heating state of the flat plate becomes difficult, and maintaining high flatness of the flat plate also becomes difficult.

When the temperature of the flat plate also increases, maintaining high flatness of the flat plate becomes difficult.

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