JP2011208821A - Vacuum furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To pursue compression of processing time in a conventional vacuum furnace, accurate quality control, optimization of a totalized control mainly intended for energy saving, and improvement of productivity.SOLUTION: A partition plate 3 surrounding a heated object while leaving a certain part opened, and a heater 4 positioned between an inner furnace wall and the partition plate 3 are provided in the furnace. A fan 7 is provided for circulating and diffusing gas heated up by the heater 4 to heat up the heated object. Circulating the gas heated up by the heater 4 through the inside and the outside of the partition plate to diffuse the gas in the furnace makes the temperature distribution of the heated object uniform, remarkably reducing the time for heating up, which achieves energy saving in heating up.

Description

  The present invention relates to a vacuum furnace that contributes to high production efficiency, high quality control, and energy saving by shortening the heating time by circulating hot air, increasing the efficiency of vacuum heating, and enabling rapid cooling using cooling water.

  In the conventional vacuum furnace, the temperature rise in the vacuum furnace is based on the fact that there is no medium for heat transfer between the heat source and the object to be heated. It is the feature.

  In order to improve this, Patent Documents 1, 2, 3, and 4 propose to shorten the temperature rising time by using a furnace gas, a fan, and a heat source. In vacuum heating, it is processed by using radiant heat from various heat sources. Regarding shortening of the cooling time, Patent Documents 2 and 4 propose to introduce a gas for cooling to lower the furnace temperature.

JP 2004-218978 A JP 2001-263957 A Japanese Patent Laid-Open No. 7-208876 Japanese Utility Model Publication No. 7-26696

  The above-mentioned Patent Documents 1, 2, 3, and 4 are effective proposals for heating an object to be heated. However, the vacuum heating of the vacuum furnaces of Patent Documents 1, 2, 3, and 4 does not exceed the point of direct use of radiant heat from a heat source. With regard to cooling, the proposals in Patent Documents 2 and 4 do not lead to significant improvement.

  Therefore, the present invention is aimed at improving efficiency and energy saving, optimizing the structure for each of the above-mentioned processes, introducing a new method, totally controlling the vacuum furnace, and dramatically improving process management and productivity. An object of the present invention is to provide an improved vacuum furnace.

  The invention according to claim 1 is provided with a partition plate in which a part to be heated is opened and surrounded in the furnace, and a heater positioned between the furnace inner wall and the partition plate, and the gas heated by the heater is circulated. And a vacuum furnace provided with a fan that diffuses and raises the temperature of an object to be heated.

  The invention according to claim 2 is provided with a cooling structure outside the furnace.

  The invention according to claim 3 is provided with a port for replacing the gas heated by the heater.

  The invention according to claim 4 is provided with an electric circuit that allows the control sensor used during the temperature increase and the control sensor used during the vacuum heating process to be independent and smoothly controlled by the temperature controller when the process is switched. It is said.

  In the invention according to claim 5, heaters are provided in four zones, up, down, left and right, respectively, so that they can be independently controlled.

  In the invention according to claim 6, the partition plate is coated with a coating that increases the radiation efficiency.

  According to the seventh aspect of the invention, after completion of the vacuum heating process, an arbitrary gas is charged into the furnace and rapidly heated by flowing the cooling water through a cooling pipe attached to the outside of the furnace and circulating the gas with a fan. It is assumed that the temperature of the object is lowered.

  The invention according to claim 8 is configured such that the rotation of the fan motor is driven in a non-contact manner by using a magnetic coupling.

  The vacuum furnace of the present invention has the above-described configuration, and in the furnace, the gas heated by the heater is circulated and diffused inside and outside the partition plate. The temperature distribution is uniform, the temperature rise time is remarkably shortened, and energy saving in the temperature rise can be realized.

It is sectional drawing from the side which can understand the flow of the sheathed heater inside a vacuum furnace, a partition plate, a fan unit, a cooling pipe, a supply / exhaust port, and a circulating wind. It is sectional drawing from the front which can understand the structure of the sheathed heater inside a vacuum furnace, a partition plate, a fan unit, and a cooling pipe. It is sectional drawing of the fan unit explaining a fan drive system.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, in each drawing, the duplication description with respect to the member which attached | subjected the same code | symbol shall be abbreviate | omitted suitably. In each drawing, members unnecessary for explanation are omitted as appropriate.

  1 to 3, FIGS. 1 and 2 are sectional views showing a sheathed heater, a partition plate, a fan unit, a cooling pipe, a supply / exhaust port and a flow of circulating air inside the vacuum furnace.

  This vacuum furnace is provided with partition plates 3 on the top, bottom, left and right so as to partially open and surround the object to be heated at an appropriate distance from the inner wall of the furnace, and the axial fan 7 is rotated so that the space between the inner wall of the furnace and the partition plate 3 is appropriate. The heated gas is circulated and diffused by using the sheathed heater 4 arranged in the heat source as a heat source to rapidly and uniformly raise the temperature of the object to be heated. In the vacuum heating process after the temperature raising process is completed, the object to be heated is heated through the partition plates that are present in the upper, lower, left, and right directions by the radiant heat from the properly disposed in-furnace sheath heater 4.

  In the cooling process, the sheathed heater 4 is turned off, an arbitrary gas is supplied into the furnace from a port provided in the vacuum furnace, and the axial fan 7 is rotated to circulate and diffuse. At that time, the cooling water is circulated through the cooling pipe 14 attached so as to be in contact with the outer wall surface of the furnace, and the temperature of the vacuum furnace body is rapidly lowered. This lowers the furnace wall surface temperature, promotes heat exchange with the circulating gas, lowers the temperature of the circulating gas, and promotes heat exchange between the circulating gas and the heated object, thereby rapidly increasing the temperature of the heated object. Lower.

  As shown in FIG. 1, a vacuum furnace according to the present invention includes a partition plate 3, a sheathed heater 4, an axial fan 7, a fan motor 8, an external magnet coupling 9A, and an internal magnet coupling in a vacuum chamber 1. 9B, a vacuum exhaust port 12, a gas supply port 13, and a cooling pipe 14 are provided, and the heat insulating effect is enhanced by the heat insulating material 2 including the door 11.

  The partition plate 3 includes upper, lower, left and right portions and a rear portion excluding the central portion, and is not provided on the front side (door 11 side). The axial fan 7 is disposed in the central open portion of the partition plate 3 at the rear, and extends from the rear to the front inside the partition plate 3 and from the front to the rear of the space between the partition plate 3 and the furnace inner wall. Form a flow. Regarding the configuration of the partition plate 3 and the axial fan 7, the front-rear and left-right relationships may be interchanged.

  The gas supply port 13 can arbitrarily introduce an inert gas and the atmosphere depending on the processing conditions of the object to be heated, and can arbitrarily introduce a circulating gas at the time of temperature rise depending on the characteristics of the object to be heated. Rapid heating of the heated object can be realized.

  First, in the temperature raising step, if heat treatment in the atmosphere is possible due to the characteristics of the object to be heated, the object to be heated is set in the vacuum chamber 1 in FIG.

  Further, when treatment under an inert gas is necessary due to the characteristics of the non-heated material, the atmosphere in the furnace is exhausted outside the furnace by opening the vacuum exhaust port 12 after the door 2 is closed. After the exhaust is completed, the vacuum exhaust port 12 is closed and the gas supply port 13 is opened, so that the circulating gas in the furnace is rapidly replaced with a gas suitable for the heating treatment of the object to be heated.

  After the rapid replacement is completed, the gas supply port 13 is closed and control for supplying the power of the sheathed heater 4 is started, and the axial fan 7 is rotated by the fan motor 8 via the magnet couplings 9A and 9B. This structure will be described later with reference to FIG. 3 which is a sectional view of the fan unit illustrating the fan driving system.

  As the axial fan 7 rotates, a circulating wind flow direction 10 is generated. At this time, the gas is heated by the sheathed heater 4 when the gas passes between the partition plate 3 attached so as to surround the object to be heated and the vacuum chamber 1. The hot air circulation is continued until an arbitrary set temperature is reached by the gas circulation control sensor 21. The effect of the heat insulating material 2 makes it possible to save energy and shorten the arrival time.

  After reaching an arbitrary set temperature, the rotation of the axial fan is decelerated and the vacuum exhaust port 12 is opened to exhaust the gas used for temperature rise out of the furnace. At this time, the electric circuit newly adopted from the gas circulation control sensor 21 smoothly shifts to the vacuum heating control sensors 22A, 22B, 22C, and 22D to perform the vacuum heating control.

  In accordance with the characteristics of the object to be heated, the temperature of the object to be heated under vacuum heating is made uniform by controlling the supply of electric power to the sheathed heater 4 by independently controlling the sensors 22A, 22B, 22C and 22D for vacuum heating control. It is possible to do.

  The heat energy supplied from the sheathed heater 4 under vacuum heating increases the emissivity in the entire wavelength region in the infrared region by the high-efficiency radiant paint coated on the partition plate 3, and directly absorbs it to the object to be heated for efficient heating. To save energy in vacuum heating. Furthermore, by adding an endothermic coating process to the heater, the efficiency of heat absorption and radiation can be improved.

  After the completion of the stable vacuum heating, the gas supply port 13 is opened, the gas corresponding to the object to be heated is filled in the furnace, the rotation of the axial flow fan 7 that has been decelerated is restored, and the circulating air flow direction 10 is generated. .

  At this time, the control for switching the vacuum heating control sensors 22A, 22B, 22C, and 22D to the gas circulation control sensor 21 and supplying the power of the sheathed heater 4 is finished.

  In order to realize temperature control with higher accuracy in the temperature raising process and the vacuum heating process, at least two thermocouples are independent, and electric power for enabling smooth control by the temperature controller at each process transition. A circuit may be provided. For example, four thermocouples may be arranged on the top, bottom, left, and right for the vacuum heating process, and each may perform independent temperature control so that heating of the object to be heated can be made uniform with high accuracy. Thereby, the stable control in each process with respect to a to-be-heated object is attained, and stable quality control can be implement | achieved.

  In addition, by providing the heaters 4 in the upper, lower, left and right zones so as to be independently controllable, it is possible to control the temperature in accordance with the shape characteristics of the vacuum furnace and the endothermic characteristics of the object to be heated from four directions. Simultaneous vacuum heat treatment of the heated object can also be realized.

  In the subsequent cooling step, cooling water is poured from the cooling water inlet 5 into the cooling pipe 14 attached so as to be in contact with the outer wall of the furnace and drained from the cooling water outlet 6. At this time, a rapid temperature drop is promoted by exchanging heat energy of the vacuum chamber 1 which has become high temperature.

  When the circulating air flow direction 10 generated by the axial fan 7 passes between the partition plate 3 and the vacuum chamber 1, heat exchange proceeds and cools between the vacuum chamber whose temperature has dropped rapidly.

  The cooled circulating wind flow direction 10 exchanges heat with the object to be heated, and rapidly accelerates the temperature drop of the object to be heated, enabling a dramatic reduction in cooling time.

  In this way, after the vacuum heating process is completed, the temperature of the object to be heated can be rapidly increased by filling the arbitrary gas into the furnace and flowing the cooling water through the cooling pipe attached to the outside of the furnace and simultaneously circulating the gas with the fan. If lowered, the amount of gas used can be drastically reduced compared to the amount of gas used in the cooling method by one-passing the cooling gas, and energy saving can be realized. Moreover, since the vacuum furnace itself can be rapidly cooled by the cooling water, a dramatic improvement in productivity can be realized by drastically shortening the cooling time.

  The driving principle of the axial fan 7 will be described with reference to a cross-sectional view of the fan unit illustrating the fan driving system shown in FIG.

  A hole is made in the back surface of the vacuum chamber 1 and the fan shaft 32 is penetrated there. The fan shaft 32 is held by a bearing unit 34 attached to the vacuum chamber 1 by a bearing bearing 31.

  The internal magnet coupling 9B is attached to the right side of the fan shaft 32 held by the bearing unit, and the axial fan 7 is attached to the opposite side.

  The fan motor 8 having the external magnet coupling 9A attached to the tip of the fan shaft 33 is attached to the motor base 35. The motor base is fixed to the vacuum chamber 1 by four motor base fixing columns.

  The external magnet coupling 9A and the internal magnet coupling 9B utilize magnetic force to enable non-contact torque transmission, are free from dust due to wear, and are very suitable for clean and vacuum environments.

  When control for supplying electric power to the fan motor 8 is started and the motor shaft 33 and the external magnet coupling 9A are rotated, the internal magnet coupling 9B also rotates while being synchronized.

  As the internal magnet coupling 9B rotates, the connected fan shaft 33 starts to rotate smoothly while being held by the bearing 31. As a result, the axial fan 7 rotates and a circulating wind flow direction 10 is generated.

  The above is the preferred embodiment of the present invention, but the present invention is not limited to the configuration of the above-described embodiment, and can be implemented by appropriately changing the shape, dimensions, material, and the like.

DESCRIPTION OF SYMBOLS 1 Vacuum chamber 2 Heat insulating material 3 Partition plate 4 Sheath heater 5 Cooling water inlet 6 Cooling water outlet 7 Axial fan 8 Fan motor 9A External magnet coupling 9B Internal magnet coupling 10 Circulating air flow direction 11 Door 12 Vacuum exhaust port 13 Gas Air supply port 14 Cooling pipe 21 Gas circulation control sensor 22A Vacuum heating control sensor upper 22B Vacuum heating control sensor right 22C Vacuum heating control sensor lower 22D Vacuum heating control sensor left 31 Bearing bearing 32 Fan shaft 33 Motor shaft 34 Bearing unit 35 Motor base 36 Motor base fixed prop

Claims (8)

  A partition plate in which a part of the object to be heated is opened and enclosed in the furnace, and a heater located between the inner wall of the furnace and the partition plate are provided, and the gas heated by the heater is circulated and diffused to dispose the object to be heated. A vacuum furnace characterized by providing a fan that raises the temperature.   The vacuum furnace according to claim 1, wherein the cooling structure is provided outside the furnace.   The vacuum furnace of Claim 1 or 2 provided with the port for replacing the gas heated with a heater.   The control sensor used at the time of temperature rising and the control sensor used at the time of a vacuum heating process are made independent, The electric circuit which enables control by a temperature controller smoothly at the time of a process switch is provided. Vacuum furnace.   The vacuum furnace according to claim 1, 2, 3, or 4, wherein the heaters are provided in four zones, top, bottom, left, and right, so that they can be independently controlled.   The vacuum furnace according to claim 1, wherein the partition plate is coated to increase radiation efficiency.   After the vacuum heating process is completed, the temperature of the object to be heated is rapidly lowered by filling the gas into the furnace and flowing the cooling water through the cooling pipe attached outside the furnace and simultaneously circulating the gas with a fan. The vacuum furnace according to claim 1, 2, 3, 4, 5 or 6. 8. The vacuum furnace according to claim 1, wherein the rotation of the fan motor is driven in a non-contact manner by using a magnet coupling.

Images