JP2004074243A - Method and apparatus for controlling temperature in hot press - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for controlling the temperature of a hot plate in a hot press in which the temperature of the hot plate is controlled by steam, and to provide an apparatus therefor. <P>SOLUTION: The method for controlling the temperature of a hot plate in a hot press 1 is provided with a hot plate 4 whose temperature is controlled by steam and a pressing apparatus for pressing the object to be worked placed on the hot plate 4. The amount of processed condensed water produced by the condensation of steam which has been used for heating of the hot plate 4 is controlled in accordance with the control stage for the hot plate 4. Concretely, the amount is made relatively large in a temperature raising stage for the hot plate 4, and is made relatively small in a temperature holding stage for the hot plate 4 by the opening and closing of a change-over valve 7. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a hot press temperature control method and apparatus for controlling the temperature of a hot plate using steam.
[0002]
[Prior art]
A conventional hot press for performing the temperature control of the present invention is indicated by reference numeral 1 in FIG. The hot press 1 arranges a plurality of hot plates 4 at equal intervals between the movable platen 3 and the fixed platen 2 when the movable platen 3 is most separated from the fixed platen 2. The work is formed by placing an object, moving the movable platen 3 close to the fixed platen 2 by a pressing device (not shown), and further pressing the movable platen. At this time, in order to control the temperature of the hot plate 4, the steam whose pressure is controlled by the steam pressure generator 12 including the control valve is heated at each hot plate 4 via the inlet manifold 5 and then collected at the outlet manifold 6. The condensed condensate is separated and drained by the steam trap 8. The condensate pipe 9 drained from the steam trap 8 is provided below the outlet of the steam trap 8 so that the condensate does not have a back pressure at the outlet of the steam trap 8. The wastewater was drained to the sewage or stored in a water tank 10 and returned to a vapor pressure generator 12 by a pump 11 as needed.
[0003]
[Problems to be solved by the invention]
According to the above prior art, the condensed water collected and condensed in the outlet manifold 6 is separated and drained by the steam trap 8, but the amount of the condensed water is not controlled and is constant. That is, since the processing capacity of the steam trap 8 is selected in accordance with the temperature raising step in which condensate occurs most, the processing capacity of the steam trap 8 becomes excessive during the temperature holding step in which condensate generation is small, and Steam leakage occurred due to the internal structure of the trap 8, resulting in energy loss.
[0004]
[Means for Solving the Problems]
Accordingly, the present invention provides a hot plate temperature control method for a hot press including a hot plate controlled by steam and a pressing device for pressing a work placed on the hot plate. The amount of condensed steam condensed is controlled in accordance with the control process of the hot plate.Specifically, the switching valve is opened and closed to increase the temperature of the hot plate relatively much, The temperature was kept relatively low in the temperature holding step.
[0005]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an outline of a hot press for implementing the present invention and its hot plate temperature control device. FIG. 2 is a graph showing the relationship between the temperature of the hot plate and the control state of the switching valve.
[0006]
As described in the section of the prior art, the hot press 1 of the present invention is the same as the conventional hot press, and the steam pressure generator 12 includes a boiler and a control valve for adjusting the pressure of steam generated from the boiler. It is a well-known thing comprised including. The pressure-regulated steam is supplied to the inlet manifold 5 and is evenly distributed from the inlet manifold 5 to the plurality of hot plates 4 via a heat-resistant and flexible hose. The steam that has heated each hot plate 4 is collected in an outlet manifold 6 and guided to a steam trap 8 via a switching valve 7.
[0007]
The steam trap 8 is a device for separating and draining condensate generated after heating the hot plate 4 and the like by depriving latent heat of condensation from steam. From the operating principle, the steam trap 8 is divided into one using the difference in specific gravity between steam and condensate, one using the temperature difference between steam and condensate, and one using the difference in specific gravity and temperature between steam and condensate. However, a mechanical trap type utilizing a specific gravity difference between steam and condensate is generally used. The mechanical trap type steam trap 8 is configured such that an open float called a bucket opens and closes a valve by buoyancy received from condensate, and condensate is discharged.
[0008]
The pipe 9 from the outlet of the steam trap 8 is connected to a water tank 10. The water stored in the water tank 10 flows into the sewage or is returned to the vapor pressure generator 12 by the pump 11. In addition, when the water tank 10 is not provided at a low position and the pressure difference between the inlet and the outlet of the steam trap 8 is not sufficient, the condensate drainage efficiency of the steam trap 8 decreases. In such a case, a vacuum pump may be connected to the outlet of the steam trap 8 to suction the condensed water.
[0009]
The switching valve 7 is a cylinder valve or the like whose opening and closing can be controlled by an electric signal. The control device 13 transmits an electric signal for controlling the opening degree of the switching valve 7 to control the amount of condensed water. The control device 13 switches at a time interval corresponding to the stroke of the hot press 1 in conjunction with a sequencer that has a second timer and controls the stroke of the hot press 1 in order to open and close the switching valve 7 at a predetermined time period. The valve 7 is opened and closed to control the flow rate of the condensed water. The switching valve 7 is not limited to the opening / closing function, but may be a valve whose opening degree can be arbitrarily changed by an electric signal. In this case, the electric signal becomes analog. The controller 13 also executes the sequence control of the hot press 1 as described above, but may also execute the temperature control of the hot plate 4 and the control of the pressing force of the movable platen 3 in addition thereto.
[0010]
The graph shown in FIG. 2 illustrates the relationship between the temperature control result of the hot plate 4 and the open / close state of the switching valve 7. As shown in the drawing, the heating plate 4 repeatedly rises and falls in temperature in each molding cycle, and at least one temperature program is set by the controller 13. Since a large amount of condensed water is discharged from the outlet manifold 6 during the temperature raising step 20 of the hot plate 4, the switching valve 7 is fully opened. After a predetermined time A from the end 21 of the temperature raising step 20, the switching valve 7 is closed and continues for a predetermined time B. After the lapse of the predetermined time B, the switching valve 7 is opened again and continues for the predetermined time C. The temperature holding step 23 is from the end 21 of the temperature raising step 20 to the end point 22 of the temperature holding in the temperature raising step 20, during which the switching valve 7 is repeatedly closed and opened at time B and time C. In the embodiment, A is 3 minutes, B is 10 minutes, and C is 1 minute. At this time, the condensed water treatment amount during the holding process 23 is 9% of the temperature-raising process at 20:00. The time A is a delay time from the end of the temperature raising process 20 to the time when the condensed water starts to decrease, and is appropriately determined according to the temperature raising temperature, the type and performance of the steam trap 8. Similarly, the time B and the time C are arbitrarily determined.
[0011]
【The invention's effect】
Since the present invention is configured as described above, a state in which water is always present in the steam trap is caused to appear, so that steam leakage can be prevented. Further, even if the steam trap breaks down and steam leaks, the amount of processing is limited according to the reduction of condensate water, so that the steam leak can be limited to the minimum, which contributes to energy saving.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an outline of a hot press embodying the present invention and a hot plate temperature control device thereof.
FIG. 2 is a graph showing a relationship between a temperature of a hot plate and a control state of a switching valve.
[Explanation of symbols]
1 Hot press 2 Fixed plate 3 Movable plate 4 Hot plate 5 Inlet manifold 6 Outlet manifold 7 Switching valve 8 Steam trap 9 …… Pipe 10… Water tank 11… Pump 12… Vapor pressure generator 13… Control device 20… Temperature rise process 21… Temperature rise end 22… Temperature retention end 23… Temperature retention process A , B, C ... time

Claims (4)

A hot plate temperature control method of a hot press including a hot plate whose temperature is controlled by steam and a pressing device for pressing a workpiece placed on the hot plate,
A hot plate temperature control method for a hot press, characterized in that the amount of condensed water condensed with steam that has heated a hot plate is controlled in accordance with a control process of the hot plate. The hot plate temperature control method for a hot press according to claim 1, wherein the condensed water treatment amount is relatively large in a heating plate temperature rising step and relatively small in a heating plate temperature holding step. The hot plate temperature control method for a hot press according to claim 1, wherein the control of the amount of condensed water is performed by opening and closing a switching valve. In a hot plate temperature control device of a hot press equipped with a hot plate whose temperature is controlled by steam, and a pressing device for pressing a workpiece placed on the hot plate,
A steam pressure generator for supplying steam of a predetermined pressure to the hot plate, a valve for controlling the flow rate of the heated steam on the hot plate together with its condensate, and a steam trap for separating and draining the flow controlled steam and the condensate. A hot plate temperature control device for a hot press, comprising:

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