JP3932953B2 - Heat stabilization device in heating device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for stabilizing a heat treatment in a heating apparatus using a steel belt heated by an induction heating coil as a heating element.
[0002]
[Prior art]
When continuously heating food or the like, a steel belt conveyor is often used. Steel baked ovens using gas heating are often used for baked goods such as cookies and cream puffs. However, there are problems such as poor energy efficiency, deterioration of working environment in terms of temperature, and safety concerns. In order to solve these problems, for example, a heating device combining a steel belt and an induction heating coil has been devised as disclosed in Japanese Patent Application Laid-Open No. 9-215605.
[0003]
[Problems to be solved by the invention]
However, a heating device that combines a steel belt and an induction heating coil has a problem that cannot be avoided in principle.
[0004]
In addition to induction heating, when a steel belt is heated, the steel belt expands according to the material and temperature of the steel belt. The expansion of the steel belt is absorbed to some extent by the tension of the springs connected to the pulleys on both ends that grip the steel belt, but it is not able to absorb partly, depending on the heating distribution, the part where the entire steel belt floats, In many cases, only the central part of the steel belt is lifted. Here, although expressed as “floating up”, the structure of a general steel belt conveyor device has a form in which the steel belt is supported from below by a number of rollers and the like, so that the steel belt moves upward from below. It is because it is easy to move. When the induction heating coil is installed below the steel belt, there is less room for the steel belt to move downward, so movement due to expansion occurs exclusively upward.
[0005]
When the steel belt is heated by gas, even if the steel belt partially moves upward or downward due to expansion, the change in the amount of heat received by the steel belt in that portion is small. However, when the steel belt is heated by induction heating, if the steel belt moves upward, the heating efficiency is remarkably lowered and the heating becomes insufficient. Furthermore, when the distance between the steel belt and the induction heating coil exceeds a specific range, the circuit becomes unloaded and heating stops. Due to these phenomena, heating of the portion that has expanded and floated becomes incomplete, and a desired heat treatment cannot be performed on the object to be heated. This phenomenon hardly occurs when the conveyor length is 5 m or less, and is likely to occur as the conveyor length increases.
[0006]
Moreover, it is easy to generate | occur | produce also by rapid heating and cooling. For example, when food is cooked on a conveyor, the temperature of the steel belt where the heated object is placed is unlikely to rise during heating due to the evaporation of moisture from the heated object. On the other hand, the steel belt temperature of the portion where the object to be heated is not placed is likely to rise. When food is heated in this way, a rapid temperature change is likely to occur near the object to be heated.
[0007]
As described above, in the case of a heating device combining a steel belt and an induction heating coil, particularly a large device having a conveyor length exceeding 5 m, a phenomenon of insufficient heating due to the steel belt rising and an increase in the temperature imbalance of the steel belt due to this. Is likely to occur, and it is difficult to maintain desired heating conditions.
[0008]
An object of the present invention is to solve the above problems and to provide a device that realizes stable heating in a heating device in which a steel belt and an induction heating coil are combined.
[0009]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have found that in the heating apparatus in which an induction heating coil is installed at the lower part of the upper steel belt of the steel belt conveyor, which is a heating surface also serving as a conveyance, the upper steel We found that heat treatment can be stabilized by using one or more rollers in contact with the belt surface and using a heat stabilization device that prevents the upper steel belt from floating during heating. did.
[0010]
Next, the heating stabilization apparatus constituting the present invention will be described sequentially.
The steel belt conveyor is a type in which a steel strip is processed into a ring shape and driven by pulling both ends with pulleys. The thickness of the steel material used as the steel belt may be a generally used 0.8 mm to 1.5 mm steel strip, but is not particularly limited as long as it is practical. The material of the steel belt widely refers to a material that generates eddy current by electromagnetic induction regardless of the expression of steel.
[0011]
The induction heating coil is a general material, for example, a rectangular copper wire arranged in a spiral shape, and is wound in a circular shape, an oval shape, a rectangular shape, etc. Widely and generally follow the methods used as induction heating coils.
[0012]
In the case of a heating device that combines these, especially a large-sized device having a conveyor length exceeding 5 m, a phenomenon of insufficient heating due to the upper steel belt floating and an increase in the upper steel belt temperature imbalance is likely to occur. It is difficult to maintain the heating conditions. This lifting can be prevented by arranging one or more rollers on the surface of the upper steel belt so that the upper steel belt does not move above the non-heated position.
[0013]
The material of the roller is not particularly limited as long as it maintains rigidity even at the highest temperature in the portion to be used and does not adversely affect the apparatus or the object to be heated. For example, when the food is heated, tetrafluoroethylene resin or the like is suitable.
[0014]
The roller needs to be thick enough to withstand at least the stress during expansion of the upper steel belt. For example, in the case of a tetrafluoroethylene resin, a thickness of 10 mm or more is desirable. Moreover, it is necessary to suppress the thickness to such an extent that it does not contact or crush the non-heated material. The roller diameter is not particularly limited.
[0015]
The method for supporting the roller is not particularly limited. In general, the shaft of the roller is connected and fixed to the apparatus housing outside the upper steel belt. The vertical position of the roller is preferably set so that the lowermost part of the roller is in contact with the surface when the upper steel belt is not heated, but it is slightly higher or lower depending on the state of expansion of the upper steel belt during heating. Can be installed. However, when installed below, excessive stress should be avoided on the upper steel belt.
[0016]
The roller may be installed at any position in the width direction of the upper steel belt. You may install in the edge part of an upper steel belt, and may install in the inner side from it. Moreover, you may install a roller in any position of the advancing direction of an upper steel belt. A suitable installation position varies depending on the apparatus shape, apparatus capacity, object to be heated, heating conditions, and the like. However, care must be taken so that the roller does not contact or crush the object to be heated.
[0017]
When the amount of meandering of the upper steel belt during heating is large, the roller may come off from the end of the upper steel belt or crush the non-heated material. In that case, it is preferable that the roller is moved following the meandering of the upper steel belt so that the relative positional relationship between the roller and the upper steel belt is maintained.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 depicts a side view of a heating device provided with the heating stabilization device of the present invention. Here, since various detailed parts of the apparatus are appropriately designed within the scope of the present invention, the drawings depict the entire structure of the apparatus in principle. As shown in FIG. 1, in the heating device 1, a steel belt 3 is stretched between two driving pulleys 2, and the upper surface of the upper steel belt 3 serves as a heating surface and a conveying surface for an object to be heated. Below the belt 3, an induction heating coil 4 is installed at an appropriate distance from the upper steel belt 3. A roller 5 which is a heat stabilization device of the present invention is installed so as to be in contact with the upper surface of the upper steel belt 3.
[0019]
The installation position of the roller 5 may be any position in the flow direction and the width direction of the upper steel belt 3, but it is desirable to install the roller 5 at an effective position for suppressing distortion of the upper steel belt 3. For example, it may be installed above the downstream end of the induction heating coil 4 as shown in FIG. When the coil 4 is disposed as shown in FIG. 1, the upper steel belt 3 is heated above the coil 4, but is not heated at all above the gap between the coils 4. Distortion is likely to occur above the downstream end.
[0020]
FIG. 2 is a front view of a heating device in which a heating stabilization device is installed at an end of the upper steel belt 3 in the width direction. The roller 5 installed so as to be in contact with the upper surface of the end of the upper steel belt 3 is fixed to a part 6 of the heating device casing by a roller support shaft 7. This installation example is suitable when the steel belt width is relatively narrow, specifically 800 mm or less and the amount of meandering is relatively small. When the steel belt width exceeds 800 mm, the central portion in the width direction of the upper steel belt 3 is raised, and there are cases where distortion cannot be eliminated simply by pressing the end portion. Further, when the amount of meandering is large, the end of the upper steel belt 3 may be detached from the roller 5.
[0021]
FIG. 3 is a front view of a heating device in which a heating stabilization device is installed at the end of the upper steel belt 3 and inside the upper steel belt 3. The roller 5 installed so as to be in contact with the end of the upper steel belt 3 and the upper surface inside the upper steel belt 3 is fixed to a part 6 of the heating device casing by a roller support shaft 7. Further, the roller 5 is installed at a position where it does not interfere with the object to be heated 8. This installation example is suitable when, for example, the steel belt width exceeds 800 mm and the central portion of the upper steel belt 3 is likely to rise, and the amount of meandering is relatively small. The number of rollers 5 installed in the width direction of the steel belt is appropriate considering the steel belt width, the shape and number of the objects to be heated 8, the passing position, the degree of distortion of the upper steel belt 3 when the roller 5 is not installed, and the like. It is good to choose a large number. However, when the amount of meandering is large, the end of the upper steel belt 3 may be detached from the roller 5 or the heated object 8 and the roller 5 may interfere with each other.
[0022]
FIG. 4 is a front view of an installation example of the heating stabilization device having a mechanism for following the meandering of the upper steel belt 3. The two-stage roller 9 is formed by concentrically bonding two rollers having different diameters, but may be cut out into a similar shape. The two-stage roller 9 is fixed to a part 6 of the heating device casing by a roller support shaft 7. A spring 10 is passed through the roller support shaft 7 so that a force that the two-stage roller 9 always follows the upper steel belt 3 is applied. Among the two-stage rollers 9, the roller with the small diameter is installed so that the side surface of the roller with the large diameter is in contact with the outer side of the upper steel belt 3 from the lateral direction so that the roller is in contact with the upper surface of the upper steel belt 3 end. Yes. In this installation example, the two-stage roller 9 is kept in contact with the end of the upper steel belt 3 by the force of the spring 10, so that the two-stage roller 9 does not come off the upper steel belt 3 following the meandering of the upper steel belt 3. However, it is necessary to adjust so that the force pressed by the spring 10 does not newly cause the meandering of the upper steel belt 3.
[0023]
FIG. 5 is a front view of an installation example of a heating stabilization device (unit type) having a mechanism for following the meandering of the upper steel belt 3. FIG. 6 is a side view thereof. This installation example is a unit type in which four rollers are arranged in two rows and connected to each other. Reference numeral 5 denotes a roller 5 supported by a roller support shaft 7, a guide roller 13 in contact with the end of the upper steel belt 3 and having a vertical rotation shaft, and a heating stabilization device support portion connected to a part 6 of the heating device housing. A heating stabilization device support roller 11 sandwiched between 12 is connected to form a unit. Even when the upper steel belt 3 meanders, the entire unit follows by the guide roller 13 following, and the relative positional relationship between the upper steel belt 3 and the roller 5 is always kept constant. The number of rollers 5 in the width direction, the number in the flow direction, and the number of units are not particularly limited.
[0024]
Further, in the unit type as shown in FIGS. 5 and 6, the meandering detection and tracking method can be made electrical. For example, a position sensor for recognizing the end of the upper steel belt 3, a motor for driving the unit in the width direction of the steel belt 3, or the like can be used. As the position sensor in this case, a photoelectric sensor, a proximity sensor, a displacement sensor, an image sensor, or the like can be used.
[0025]
【Example】
A carbon-quenched steel steel belt having a thickness of 1.2 mm, a width of 1 m, and a length of 60 m was endlessly processed and pulled on two 800 mm diameter and 800 mm width pulleys to obtain a steel belt conveyor having a total length of about 30 m. Next, 10 induction heating coils that fit in a 1 m square unit were created and arranged in the rear 11 m portion of the upper steel belt, 10 mm below the upper steel belt. The gap between the coils was about 100 mm. Each coil unit was connected to a 30 kW induction heating inverter. A temperature sensor was installed on the back surface of the central portion in the width direction of the upper steel belt at a position 50 mm downstream of each coil unit. This temperature sensor was installed so as to be always in contact with the back surface of the upper steel belt by a spring, and the measured value was sent to the temperature controller to control the output of the induction heating inverter corresponding to the coil unit adjacent on the upstream side. With these temperature sensors and temperature controllers, any temperature setting was realized.
[0026]
With this heating device, the belt speed is 3 m / min, and the set temperature of each coil unit is 120 ° C, 120 ° C, 120 ° C, 160 ° C, 160 ° C, 160 ° C, 200 ° C, 200 ° C, 200 ° C, in order from the upstream side. It started as 220 degreeC. Two minutes after the start of heating, distortion of the upper steel belt and lifting of about 20 mm were observed after the middle portion of the 11 m portion where the coil was installed. When the upper steel belt floats up, the induction heating circuit of that part is cut off and heating stops, and the phenomenon that the coil approaches and reheats as the heating stops and the temperature of the upper steel belt decreases occurs irregularly. did. FIG. 9 shows the temperature change of the back surface of the central part in the width direction of the upper steel belt 50 mm downstream of the seventh coil unit from the upstream side at that time (up to 15 minutes after starting). It can be seen that an irregular temperature fluctuation occurs with respect to the set temperature of 200 ° C. When the object to be heated was heated, things that were over-baked or insufficiently baked occurred irregularly, and stable heat treatment could not be performed.
[0027]
Therefore, a unit-type heat stabilization device as shown in FIG. 7 (plan view) and FIG. 8 (side view) was manufactured. In a unit occupying almost the same area as the 1 m square induction heating coil 4, ten rollers 5 are supported by three roller support shafts 7. The position of the roller 5 was adjusted to a position that does not interfere with the heated object 8 that is flowed in five rows, and the roller 5 was disposed only in an effective portion in order to reduce the manufacturing cost. The entire unit is supported by a heating stabilization device support rod 14 connected to the heating device housing, and can be operated in the steel belt width direction by a heating stabilization device support sliding portion 15. Since the guide roller 13 moves following the end of the upper steel belt 3, the relative positions of the roller 5 and the upper steel belt 3 are maintained even when the upper steel belt 3 meanders.
[0028]
When five heating stabilization devices were prepared and installed on every other induction heating coil, and heating was started in the same manner, the upper steel belt was distorted and lifted immediately after the start until the heating was stopped after 5 hours. Was suppressed and stable heating was achieved. FIG. 10 shows the temperature change of the back surface of the central portion in the width direction of the upper steel belt 50 mm downstream of the seventh coil unit from the upstream side (from 15 minutes after starting). It can be seen that the temperature changes stably with respect to the set temperature of 200 ° C. When the object to be heated was poured and heated, a desired baking condition was stably obtained.
[0029]
【The invention's effect】
According to the present invention, in a heating apparatus in which an induction heating coil is installed below the upper steel belt of the steel belt conveyor, which is a heating surface that also serves as a conveyance, one or more rollers that contact the surface of the upper steel belt are arranged, By preventing the upper steel belt from lifting up, stable heating can be achieved. Furthermore, since the roller moves following the meandering of the upper steel belt, the relative positional relationship between the roller and the upper steel belt is maintained, and the object to be heated is not crushed. By these, the principle subject which the heating apparatus which combined the upper steel belt and the induction heating coil has is solved, and the outstanding effect that it becomes a reliable heating apparatus even if it operates for a long time can be acquired.
[Brief description of the drawings]
FIG. 1 is a side view of a heating device provided with a heating stabilization device of the present invention.
FIG. 2 is a front view of a heating device in which a heating stabilization device is installed at an end portion in the width direction of the upper steel belt.
FIG. 3 is a front view of a heating device in which a heating stabilization device is installed at an end portion and an inner side in the width direction of the upper steel belt.
FIG. 4 is a front view of an example in which a heating stabilization device having a mechanism for following the meandering of the upper steel belt is installed.
FIG. 5 is a front view of an example in which a heating stabilization device (unit type) having a mechanism for following the meandering of the upper steel belt is installed.
FIG. 6 is a side view of an example in which a heating stabilization device (unit type) having a mechanism for following the meandering of the upper steel belt is installed.
FIG. 7 is a plan view of an embodiment of a heating stabilization device (unit type) having a mechanism for following the meandering of the upper steel belt.
FIG. 8 is a side view of an embodiment of a heating stabilization device (unit type) having a mechanism for following the meandering of the upper steel belt.
FIG. 9 is an example of the transition of the upper steel belt back surface temperature when no heat stabilization device is installed.
FIG. 10 is an example of the transition of the back surface temperature of the upper steel belt when the heating stabilization device of FIGS. 7 and 8 is installed.

Claims (3)

In a heating device in which an induction heating coil is installed in the lower part of the upper steel belt of the steel belt conveyor, which is also a heating surface that also serves as a conveyance, one or more rollers that are in contact with the upper steel belt surface are arranged, A heating stabilization device characterized by preventing floating. The heat stabilizing device according to claim 1, wherein the roller moves relative to the meandering of the upper steel belt to maintain a relative positional relationship between the roller and the upper steel belt. The roller is a two-stage roller in which two rollers with different diameters are concentrically bonded, and the side of the roller with the larger diameter is at the end of the upper steel belt so that the roller with the smaller diameter contacts the upper surface of the upper steel belt end. The heat stabilization apparatus according to claim 1, wherein the heat stabilization apparatus is installed so as to be in contact with the outside of the apparatus from a lateral direction.

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