JP2011149559A - Heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heating device capable of properly heating a metallic workpiece such as casting before coating at a high speed with high heat efficiency, and further suppressing equipment costs and an installation area without developing defects on the coating thereafter. <P>SOLUTION: This heating device applies a powder and granular material as a heat medium, includes fluid beds 3, 4 in which the workpiece is immersed, and a hot air generator 11 generating hot air, and distributing the hot air to the fluid beds to heat and fluidize the heat medium, uses an electrothermal heater as a heating heat source of the hot air generator 11, and is constituted to recover the exhaust gas discharged from the fluid beds 3, 4 and distributing the same to the fluid beds 3, 4 again. Thus, the workpiece can be stably heated at a high speed, and the heat efficiency can be improved. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a heating apparatus that heats a metal workpiece such as a casting before painting.

  Cast parts coated for rust prevention or the like are used for a pipe line through which a liquid such as water is sent and a valve box of a valve provided in the pipe line. This casting is heat-treated before coating in order to improve the processing speed in the coating process and to ensure the coating quality.

  To describe this in detail, there are two methods for painting casting parts and the like: a method using a liquid paint and a method using a powder paint, and a method using the liquid paint. Examples of the method include immersion, brush coating, spray coating, electrostatic coating, and the like. Examples of the coating method using the powder coating include sprinkling coating, spray coating, fluidized bed immersion coating, electrostatic coating, and the like. The casting is painted by the painting method. When performing any of these coating methods, it is required to improve the quality of the coating film by reliably applying paint and forming a film, and heating in the film forming process and the curing process. It is desired to increase the processing speed to improve the production efficiency, and as a process corresponding to these demands, pre-coating heating (pre-heating process) for heating the casting material in advance is performed.

  The heating temperature for this pre-coating heating is set taking into account the temperature drop in the casting material, the composition of the painting line for painting the casting material, and the painting line so that it can be processed at the optimum temperature corresponding to the type of paint and the painting method. Is done.

  As a conventional heating device for performing this pre-coating heating, etc., a combustion gas atmosphere furnace is mainly used which generates a combustion gas using gas or oil as a fuel and heats a workpiece which is a heating object such as a casting with the combustion gas. (For example, Patent Document 1) is used. In addition, a warm water heating tank etc. are also used when heating temperature may be 100 degrees C or less.

  However, in the pre-coating heat treatment that is performed before coating with the resin-based paint, the heating temperature may be less than 300 ° C., but when heating for powder coating, about 150 is required to melt the paint. Since it is necessary to be able to be heated to a temperature equal to or higher than ° C., heating is mainly performed by convection heat transfer using a combustion gas having a small heat capacity as a heat medium.

JP 2009-57621 A

  However, when using a heating device that uses combustion gas as the heat medium, the stored heat of the recovered exhaust gas is recovered with a heat exchanger, or fresh cold air is always replenished to supply the oxygen necessary for fuel combustion. Therefore, there is a drawback that the equipment cost for the heat exchanger is increased and the thermal efficiency is lowered. In addition, if the heat treatment speed is increased by using a heating device that heats the combustion gas having a small heat capacity as a heat medium by convection heat as described above, a long heating path is required and a large heating furnace is required. In addition to the extremely high equipment costs, there are also disadvantages that a large installation area is required.

  In addition, if the casting material is transferred after heat treatment using combustion gas as a heat medium in a high-speed conveying line, gas such as combustion gas easily enters under the molten coating film due to the surface characteristics of the casting. There is also a problem that the gas expands after the film is formed to cause a coating defect.

  The present invention solves the above-mentioned drawbacks and problems, and can heat a metal workpiece such as a cast before coating satisfactorily at high speed and high thermal efficiency, and does not cause subsequent coating defects. Another object of the present invention is to provide a heating apparatus that can reduce equipment costs and installation area.

  In order to solve the above disadvantages and problems, the present invention is a heating device for heating a metal workpiece, wherein the granular material is used as a heat medium, a fluidized bed in which the workpiece is immersed, hot air is generated and the fluidized bed Hot air generating air blowing means that heats and heats the heat medium sent in, the heating heat source of the hot air generating air blowing means is an electric heater, and collects exhaust gas discharged from the fluidized bed by the hot air generating air blowing means It is characterized in that it is sent again to the fluidized bed.

  According to this configuration, since the work is immersed and heated in a fluidized bed using the granular material as a heat medium, the casting before coating can be heated at high speed and good thermal efficiency. In other words, since the work is immersed and heated in a fluidized bed with powder particles as the heat medium, the work is stabilized at high speed evenly from the entire surface, without causing local overheating, etc. Thus, the installation space can be kept relatively small. Further, since the heating heat source is an electric heater, even if hot air heated by the electric heater is introduced into the fluidized bed and heated, the retained heat of the recovered exhaust gas is retained as in the case of introducing the combustion gas. There is no need to collect it with a heat exchanger or to introduce oxygen or cold air to use it for combustion air, and the exhausted hot air is recovered and circulated to maintain extremely high thermal efficiency. be able to.

  Further, the heating device of the present invention has, as a fluidized bed, a fluidized bed for raising the temperature of the workpiece rapidly, and a fluidized bed for soaking that adjusts the heated workpiece to a predetermined temperature. Features.

  According to this configuration, since the temperature of the workpiece is rapidly raised in the fluidized bed for temperature rise, the workpiece can be heated quickly and the processing efficiency can be improved, and the temperature is raised in the fluidized bed for soaking. Since the workpiece is adjusted to a predetermined temperature, the final workpiece temperature can be adjusted with high accuracy, and the reliability of the heat treatment is improved.

  Further, the heating device of the present invention includes a conveying means for conveying a workpiece, and the conveying means conveys the workpiece along a predetermined conveying path while taking in and out the fluidized bed at an arbitrary position in the conveying path. It is configured to move in a free state.

  With this configuration, it is possible to easily adjust the time during which the work is taken in and out of the fluidized bed, so that it is possible to heat various kinds of work well and accurately according to the size and heat capacity.

  Further, the present invention is characterized in that the conveyance path is formed in a loop shape or a U-shape, and a fluidized bed is disposed in the middle of the conveyance path along the conveyance path. With this configuration, it is possible to reduce the overall length of the apparatus and reduce the installation area as compared with the case where the conveyance path is configured in a straight line.

    In addition, the present invention is characterized by comprising control means for controlling the timing of loading and unloading the workpiece into the fluidized bed. With this configuration, it is possible to accurately adjust the time during which the work is taken in and out of the fluidized bed, so that the work can be heated well and accurately according to the size and heat capacity of various works.

  Moreover, it is preferable to use ceramic particles as the heat medium, the workpiece can be heated well and with high thermal efficiency, consumption due to use can be minimized, and maintenance costs can be reduced.

  In addition, it is particularly suitable when the workpiece is a casting before painting, and the casting before painting can be heated very well, and in the subsequent painting process, painting is performed when combustion gas is used as a heat medium. Since no defects are produced, high coating quality can be obtained.

  According to the present invention, since the work is immersed and heated in a fluidized bed using the granular material as a heat medium, local overheating or the like occurs at a high speed and evenly from the entire surface as compared with a gas atmosphere furnace or the like. And can be heated stably. By using an electric heater as the heating heat source of the hot air generating air blowing means, the discharged hot air can be collected and used in a circulating manner, and the thermal efficiency can be improved.

  In addition, the fluidized bed has a structure in which a fluidized bed for raising the temperature of the workpiece is heated rapidly and a fluidized bed for soaking the heated workpiece to a predetermined temperature. In the fluidized bed, the workpiece can be heated quickly and the processing efficiency can be improved, but in the fluidized bed for soaking, the heated workpiece is adjusted to the specified temperature, so the final workpiece temperature is accurate. It can be adjusted well and reliability is improved.

  In addition, the conveying means is configured to move the workpiece in a fluidized bed while moving the workpiece along a predetermined conveying path so that the workpiece can move in and out of the fluidized bed at an arbitrary position in the conveying path. Since the time for taking in and out and soaking can be easily adjusted, heating can be performed well and accurately according to the size and heat capacity of various workpieces. In addition, a large number of workpieces can be processed continuously, and a high processing capacity can be obtained.

  In addition, when the workpiece is a casting before painting, the casting before painting can be heated extremely well, and in the subsequent painting treatment, a coating defect occurs when combustion gas is used as a heat medium. High coating quality can be obtained.

It is a top view of the heating apparatus which concerns on embodiment of this invention. It is a partially cutaway front view of the heating device. It is a right view of the heating device. It is a figure which shows the flow etc. of the heat medium of the heating apparatus. It is a figure which shows the flow etc. of the workpiece | work of the heating apparatus. It is right side sectional drawing which shows the flow etc. of the workpiece | work of the heating apparatus.

Hereinafter, a heating device according to an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1 to FIG. 6, the heating device according to the embodiment of the present invention is a heating device that heats a metal workpiece 1 such as a casting before coating, and a granular material 2 made of ceramic particles. Two fluidized beds 3 and 4 serving as heat mediums, hot air generating air blowing means for generating hot air and sending the fluidized layers 3 and 4 to heat and flow the granular material 2, and the workpiece 1 along a predetermined conveying path A conveying means such as an electric chain block 23 that moves in a freely movable state with respect to the fluidized beds 3 and 4 in the conveying path in the conveying path, and is substantially U-shaped in plan view. Surrounding the exhaust gas discharged from 3 and 4 so as not to leak to the outside, a cylindrical heat retaining duct (duct portion) 5 serving as a conveyance path for the workpiece 1 is provided.

  Each fluidized bed 3, 4 has a large number of hot air jet pipes 6 arranged in the lateral direction at the bottom of the substantially box-shaped tank bodies 3 a, 4 a in which the powder particles 2 are stored, having many holes through which hot air is jetted upward. The granular material 2 is heated and fluidized by the hot air discharged from the hot air jet pipes 6. In FIG. 1 and the like, 6a is the header of the hot air jet pipe 6, 7 in FIG. 4 is a fluidized bed temperature sensor for detecting the temperature of the storage part of the granular material 2 in the fluidized beds 3 and 4, and 8 is the fluidized beds 3 and 4. It is a fluidized bed space part detection sensor which detects the temperature of the space part above the storage part of the granular material 2 in. The upper surface of each fluidized bed 3, 4 can be opened and closed by a lid 9 driven by an air cylinder or the like. In principle, when the workpiece 1 is in the fluidized bed 3, 4, the lid 9 is opened, and the lid 9 is closed when there is no work 1 in the fluidized beds 3 and 4.

  As shown in FIG. 4 and the like, the hot air generating air blowing means recovers the exhaust gas discharged from the fluidized beds 3 and 4 and flowing into the heat retaining duct 5 through the exhaust recovery pipe 12a, and thereby fluidized beds 3 and 4. And a hot air generator 11 composed of an electric heater (block heater) that heats exhaust gas sent from the blower 10 and air taken in from the outside, and from the hot air generator 11 Hot air is sent to the hot air jet pipe 6 (see FIG. 5) of the fluidized beds 3 and 4. A hot air temperature sensor 13 is provided at the outlet of the hot air generator 11 and the like, so that hot air having a predetermined temperature can be generated from the hot air generator 11. In addition, it is comprised so that a clean air can also be introduce | transduced into a hot-air generation ventilation means through the air filter 14 as needed. The exhaust recovery pipe 12 is provided with flow rate adjustment dampers 15A and 15B and an inflow side temperature detection sensor 17 capable of adjusting the inflow amount of exhaust gas and the inflow amount of air. In FIG. 4, reference numeral 16 denotes a dust collection filter that removes collected exhaust, and 10 a denotes a motor that drives the blower 10.

  Here, as shown in FIG. 4, only the hot air generated by the hot air generator 11 is sent to the fluidized bed 3 through the hot air delivery pipe 12 b, and the fluidized bed 3 rapidly raises the temperature of the workpiece 1. The fluidized bed 3 is used for heating. On the other hand, the hot air generated by the hot air generator 11 and the recovered circulating hot air or air sent out from the blower 10 are mixed into the fluidized bed 4 by the mixer 18 and the hot air adjusted to a predetermined temperature is sent to the fluidized bed 4. The layer 4 is a fluidized bed 4 for soaking that adjusts the workpiece 1 heated in the fluidized bed 3 for temperature rise to a predetermined temperature. In FIG. 4, 12 c is a hot air sending pipe for sending hot air from the hot air generator 11 to the fluidized bed 4 side, and 12 d is an air sending pipe for sending exhaust gas and air sent from the blower 10 to the fluidized bed 4 side. Pipes 15c and 15d are flow rate adjustment dampers provided in the pipes. The flow rate adjustment damper 15c adjusts the amount of hot air from the hot air delivery pipe 12c so that the temperature is set by a temperature controller (not shown).

  The conveying means is capable of self-propelling while being guided by the traveling rail 21 disposed in a loop shape in a plan view above the heat retaining duct 5, and is capable of moving the workpiece 1 via the chain 22. A plurality of (for example, six) electric chain blocks 23 suspended so as to be able to move up and down are provided, and each electric chain block 23 is configured to be able to recognize the traveling position of the traveling rail 21. Each electric chain block 23 is immersed in each fluidized bed 3 and 4 at a position indicated by the control unit while traveling along the traveling rail 21 by a control unit (not shown). When the time specified by the control unit comes (or reaches a designated position), the fluidized beds 3 and 4 are lifted into the heat retaining duct 5. The electric chain block 23 does not necessarily have to be self-propelled, and may be configured to move by receiving a driving force such as a driving chain that is moved along the traveling path.

  Further, 5a in FIG. 4 is a duct inlet part into which the work 1 suspended by the electric chain block 23 is introduced, and 5b is a duct outlet part from which the work 1 suspended by the electric chain block 23 is discharged. Each electric chain block 23 is introduced from the duct inlet 5b in the A direction (see FIGS. 1 and 5), passes through the heat insulation duct 5, and is immersed in the fluidized bed 3 for temperature rise, and then again the heat insulation. It passes through the middle part of the duct 5 and is immersed in the fluidized bed 4 for heat equalization, and is discharged from the duct outlet part 5b through the heat retaining duct 5 in the B direction (see FIGS. 1 and 5).

  Further, the duct inlet portion 5a, the inlet and outlet portions to locations corresponding to the fluidized beds 3 and 4 in the heat retaining duct 5, and the region 5c in which the work 1 is blown in the heat retaining duct 5 (see FIG. 5). The door portion 26 and the duct outlet portion 5b are provided with doors 26 that can prevent the exhaust from the fluidized beds 3 and 4 from flowing out to reduce the thermal efficiency. The door body 26 is opened only when passing through a place to be performed. In this embodiment, the door body 26 is shown as being opened and closed by an air cylinder, but is not limited to this configuration.

  In this embodiment, the air purified through the air filter is heated to a high temperature through the heating pipe 27 disposed at the bottom of the fluidized bed 3, and the hot air is removed from the sand (heat medium removal). ) Air blow device 28 and air curtain 29, and heated workpiece 1 is washed with warm air, and the outflow of powder body 2 as a heat medium to the outside is minimized.

  In the above configuration, the workpiece 1 to be heated is suspended from a hook (locking portion) or the like of the electric chain block 23 at a location before the duct inlet 5a and introduced into the heat retaining duct 5 from the duct inlet 5a. Is done. And when it is conveyed above the fluidized bed 3 for temperature rise, it is lowered into the fluidized bed 3 for temperature rise and immersed in the fluidized bed 3 for temperature rise while continuing the conveying operation. Then, when the workpiece 1 reaches a predetermined position (or reaches a predetermined time), the workpiece 1 is taken out from the fluidized bed 3 for temperature increase. Thereafter, after passing through the intermediate portion of the heat insulation duct 5, when the position reaches the upper position of the soaking fluidized bed 4, the chain 22 is lowered and the work 1 is immersed in the soaking fluidized bed 4. When it reaches a predetermined position (or reaches a predetermined time), it is taken out from the fluidized bed 4 for soaking, and then discharged from the duct outlet 5b through the heat retaining duct 5. Here, the control unit recognizes in advance the immersion time of each work 1 in the fluidized beds 3 and 4 corresponding to the heat capacity of each work 1, and the temperature is increased so as to be the immersion time. Each electric chain block 23 is instructed to be controlled so as to be in the input position and the extraction position in the fluidized bed 3 and the soaking fluidized bed 4.

  According to the above configuration, since the work 1 is moved and heated while being immersed in the fluidized beds 3 and 4 using the granular material 2 as a heat medium, the work 1 such as a casting before coating is fast and has good thermal efficiency. And it can heat stably, without producing local overheating. That is, since the work 1 is immersed and heated in the fluidized beds 3 and 4 using the granular material 2 as a heat medium, the work 1 is faster than a gas atmosphere furnace (three times or more than the gas atmosphere furnace). It is possible to stably heat from the entire surface without causing local overheating, and the installation space can be kept relatively small. In addition, since the heating heat source is the hot air generator 11 composed of an electric heater, the combustion gas is introduced even if the hot air heated by the electric heater is introduced into the fluidized beds 3 and 4 and heated. Thus, it is not necessary to recover the retained heat of the recovered exhaust gas with a heat exchanger, or to introduce oxygen or cold air to use it for combustion air, and it is discharged from the fluidized beds 3 and 4 By collecting hot air from the heat retaining duct 5 and circulating it while heating it with the hot air generator 11, extremely high thermal efficiency can be maintained.

  Further, according to the above configuration, first, the temperature of the workpiece 1 is rapidly raised in the fluidized bed 3 for raising the temperature, so that the workpiece 1 can be heated quickly and the processing efficiency can be improved. In the fluidized bed 4, the heated workpiece 1 is adjusted to a predetermined temperature, so that the final temperature of the workpiece 1 can be accurately adjusted, and the reliability of the heat treatment is improved. Note that the heating temperature in the soaking fluidized bed 4 is not necessarily set higher than the final heating temperature of the temperature rising fluidized bed 3 and may be a low temperature.

  In addition, as described above, since the work 1 is conveyed in an arbitrary position with respect to the fluidized beds 3 and 4 by the conveying means including the electric chain block 23 and the like, the workpiece 1 is transferred to the fluidized beds 3 and 4. It is possible to easily adjust the time for putting in and out of 4 and soaking, and it is possible to heat various workpieces 1 well and accurately according to their sizes and heat capacities. In addition, as described above, by providing a control unit that controls the timing of loading and unloading the workpiece 1 into and from the fluidized beds 3 and 4, the time for allowing various workpieces 1 to be loaded and unloaded into and from the fluidized beds 3 and 4 can be accurately set. It can be adjusted and can be heated well and accurately according to the size and heat capacity of various workpieces 1.

  Further, since the transport path is formed in a loop shape or a U-shape, and the fluidized beds 3 and 4 are disposed along the transport path, the heating apparatus is compared with the case where the transport path is configured in a straight line. The overall length can be kept small, and the installation area can be saved.

  In addition, since ceramic particles are used as the heating medium of the granular material 2, the workpiece 1 can be heated satisfactorily and with high thermal efficiency, and consumption due to use can be minimized. Can be reduced.

  Further, when the workpiece 1 is a casting before painting, the workpiece 1 that is a casting before painting can be heated extremely well, and the workpiece 1 is rapidly heated by the fluidized bed 3 for temperature rise. After that, since the temperature is adjusted to a temperature suitable for coating the workpiece 1 with the fluidized bed 4 for soaking, the generation of gas from the workpiece 1 in the subsequent coating process can be prevented, and the combustion gas is used as the heat medium. There is an advantage that high coating quality can be obtained and reliability is improved without causing a coating defect as in the case. The workpiece 1 of the present invention is particularly suitable for a cast before painting, but is not limited to this, and can be applied to other metal workpieces 1.

1 Workpiece (casting before painting)
2 Powder (Heat medium: Ceramic particles)
3 Fluidized bed (fluidized bed for heating)
4 Fluidized bed (fluidized bed for soaking)
5 Thermal insulation duct (conveyance route: duct part)
6 Hot-air jet pipe 10 Blower 11 Hot-air generator (electric heater)
16 Dust collection filter 21 Traveling rail 22 Chain 23 Electric chain block (conveying means)

Claims (7)

A heating device for heating a metal workpiece,
A fluidized bed in which the powder is used as a heat medium and the workpiece is immersed,
Hot air generating air blowing means for generating hot air and sending it to the fluidized bed to heat and flow the heat medium;
With
A heating apparatus characterized in that a heating heat source of the hot air generating air blowing means is an electric heater, and the exhaust gas discharged from the fluidized bed is collected by the hot air generating air blowing means and sent again to the fluidized bed.   2. The heating according to claim 1, wherein the fluidized bed has a fluidized bed for raising the temperature of the workpiece rapidly and a fluidized bed for soaking the temperature of the heated workpiece to a predetermined temperature. apparatus.   A conveying means for conveying the workpiece is provided, and the conveying means is configured to move the workpiece along a predetermined conveying path so that the workpiece can be freely moved in and out of the fluidized bed in the conveying path. The heating device according to claim 1, wherein the heating device is provided.   The workpiece conveyance path is formed in a loop shape or a U-shape, and a fluidized bed is disposed in the middle of the conveyance path along the conveyance path. Heating device.   The heating apparatus according to any one of claims 1 to 4, further comprising a control unit that controls a timing of loading and unloading the workpiece into and from the fluidized bed.   The heating apparatus according to any one of claims 1 to 5, wherein ceramic fine particles are used as the heat medium.   The heating apparatus according to any one of claims 1 to 6, wherein the workpiece is a cast before painting.

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