US3646992A

US3646992A - Method for heating pressing plates of continuous flat press

Info

Publication number: US3646992A
Application number: US886525A
Authority: US
Inventors: Kazutomo Ishizawa; Yasunori Nagata; Junnosuke Abe; Akira Fukuoka
Original assignee: Kanegafuchi Spinning Co Ltd
Current assignee: Kanegafuchi Spinning Co Ltd
Priority date: 1968-12-29
Filing date: 1969-12-19
Publication date: 1972-03-07
Anticipated expiration: 1989-03-07
Also published as: JPS4949232B1; DE1964172A1; CH497593A; FR2027290A1; NL141255B; US3609891A; GB1256159A; NL6919480A

Abstract

Method for heating pressing plates of a continuous flat press for maintaining surface temperature thereof below 100* C. by utilizing steam. The inside pressure of a conduit disposed in said pressing plate is maintained at a predetermined pressure below an atmospheric pressure while supplying steam into said conduit. And it is preferably applied for carrying out the present method that the partial pressure of air in said conduit is discharged before supplying said steam into said conduit.

Description

United States-Patent Ishizawa et al.

[ 51 Mar. 7, 1972 METHOD FOR HEATING PRESSING PLATES OF CONTINUOUS FLAT PRESS Inventors: Kazutomo lsliizawa; Yasunori Nagata;

Junnosuke Abe, all of Osaka; Akira Fuknoka, Tokyo, all of Japan Assignee: Kanegafuchi Boseki Kabushiki Kaisha,

Tokyo, Japan Filed: Dec. 19, 1969 Appl. No.: 886,525

Foreign Application Priority Data Dec. 29, 1968 Japan ..43/96481 US. Cl ..l65/l, 165/111, 165/32, 100/93 P Int. Cl ..F28d 7/10 FieldofSearch ..l65/l,32,39,111,168,71; 100/93 P [56] References Cited UNITED STATES PATENTS 1,847,573 3/1932 Rupp ..l65/l68 X 3,525,098 8/1970 Vox ..l65/48 X Primary Examiner-Frederick L. Matteson Assistant Examiner-W. C. Anderson Attorney-Robert E. Burns and Emmanuel J. Lobato [.57] ABSTRACT Method for heating pressing plates of a continuous flat press for maintaining surface temperature thereof below 100 C. by utilizing steam. The inside pressure of a conduit disposed in said pressing plate is maintained'at a predetermined pressure below an atmospheric pressure while supplying steam into said conduit. And it is preferably applied for carrying out the present method that the partial pressure of air in said conduit is discharged before supplying said steam into said conduit.

2 Claims, 2 Drawing Figures PAIENTEDHAR 7 I972 TEMPERATURE OF HOT WATER TEMPERATURE OF PRESSING PLATE OUTLET OF HOT WATER INLET OF HOT WATER ATTORNEY METHOD FOR HEATING PRESSING PLATES OF CONTINUOUS FLAT PRESS The present invention relates to an improved. method for heating pressing plates of continuous flat press at a temperature below 100C. by utilizing steam.

Generally, in the finishingprocess of textile fabrics such as worsted or woolen fabrics, certain union fabrics made. of worsted or woolen yarn or-blended yarn containing thesame synthetic fibers, pressingof the'fabrics must be appliedfor glazing, providing dimensional stability and improving. hand feeling of the fabrics. It is well known that a paper-pressing method has been applied, for the above-mentioned purpose.

The paper-pressingv operation applied to high-quality worsted fabrics is inevitable for attainingvery elegant luster and good hand feeling. However, a fairly long time is required to complete the above-mentioned paper-pressing operation and moreover, the folds of the fabric are free from the paper'- pressing operation. Therefore, in the paper-pressing operation, it is required to transfer the fabric, which has completed a first operation, to a lift table and at the same time, the insertion of the press papers are required to be changed;

For carrying out the above-mentioned paper-pressing operation in the conventional paper-pressing equipment, a plurality of presses and lifts are required to be. used.

To eliminate the above-mentioned drawbacks involved in.

the paper-pressing method, a now well-known continuousflat press such as Hattersley Pickard-Flat Press was developed and these machines are now being practically applied. for the continuous pressing operation. In a unit operation, a fabric is.-

held by a pair of press-plates under heat while one of the pressing plates is pushed to the other pressing plate by;utilizing pneumatic or oil pressure, the fabric just completed in the pressing operation is moved forward by a predetermined distance while the pressing action by the two press-platesis.

released. The above-mentioned operations are alternately carried out intermittently. By utilizing the above-mentioned continuous flat press, the pressing operation of the fabric can be carried out speedily and efficiently.

Generally, in the pressing operation of the fabric for providing luster thereof, pressure, temperature, humidity contained. in thefabric, and operating time are veryimportant factors to carry out the pressing operation. In these importantfactors, it is particularly required to control the temperature of the pressing operation. Heating of the pressing plates is carried out by supplying a heating medium into a heating conduit or conduits formed therein. In case the required temperature of the pressing plate is higher than 100 C., steam is used as the heating medium, while in case. the required temperature is below 100 C., hot water is used as the heating medium. However, in the latter case, the surface temperature of the pressing plate is very difficult to maintain in a uniform condition, and it.

is required to supply the hot water with a high flow rate for preventing the irregular distribution of the surface temperature of the pressing plate.

The principal object of the present invention is to provide an improved heatingmethod of the pressing plates of the continuous flat press wherein the pressing plates are always maintained at a uniform temperature below l C. with high heating efficiency.

Further features and advantages of the invention will be apparent from the ensuing description with reference to the accompanying drawings to which the scope of the invention is no way limited.

FIG. 1 is an explanatory diagram for illustrating the dropping of the temperature of the hot water supplied into a conduit formed in a pressing plate when the surface temperature of the pressing plate is maintained at a uniform, constant value,

FIG. 2 is a schematic diagram of a heating device applied to the pressing plate of the continuous flat press, according to the present invention.

For better understanding of the present invention, firstly, the drawback of the heating method applied to the conventional flat press is analytically illustrated.

Now, aconventionalpressing platemaintaining its temperature at C. by supplying hot water, is considered. The required quantity of heat for maintaining the pressing plate at 95 C. is supposed to be 7,000 KcaL/hour. In the above-mentioned condition, the followingequation is obtained:

Q: quantity of heat required to maintain the temperature of a pressing plate at'95 C.

U: heattransfer coefficient with respect to transmitting heat energy'from the hot water to the pressing plate made of iron.

A: area of heat transmission of a conduit for flowing the hot water (dia. of the conduit =22 mm.

W: flow rate ofthe circulation of the hot water kg./hr.

C,: specific heat at constant pressure KcaL/kg. C.

A0,: difference between a temperature of the hot-water at an entrance of the conduit and that of the pressing plate.

A0 difference between atemperature of the hot water at an outlet of theconduit and that of the pressing plate.

A0 differencebetween a temperature of the hot water at the inlet of the conduit and that at the outlet of the conduit;

The relation between 0,, 0 and 0;, is shown in FIG. 1. Referring to FIG. 1, and assuming that'the differential temperature A0, is 4 C. with the. following measured data: Q=7,000 Kcal./hr., U=340 KcalJ/m. hr. C., and A=l .3 m.; then,

As isclearly understood from the above-mentioned calculation, to maintain the pressingplate at 95 C. it is necessary to continuously supply hot water of l35 C. at a flow rate of 32.1 kg./min. In other. words, the temperature of the hot water supply is about 40 C. higher than that of the pressing plate, moreover, the flow rate of 32.1 kgJmin. is a distinctly, large quantity of hot water, which is a required supply for maintaining the temperature of the pressing plate at 95 C.

In fact, there is a certain limitation for enlarging the area A of the heattransmission of the conduit, because of the construction of the pressing plate.

Therefore, it is required to make A0, as large as possible for transmitting a sufficient quantity of heat Q from the hot water to the pressing plate. In other words, in the case of heating the pressing plate at 80 C. C. by utilizing hot water in a uniform condition, it is quite certain that a quantity of exchange heat between the hot water in the conduit and the pressing plate is insufficient for attaining the uniform condition of the pressing plate even though the difference between the temperature of the hot water at the inlet of the conduit and that at the outlet of the conduit is very large.

The principle of the present invention is based upon a fact that it is capable of heating the pressing plate uniformly by steam, provided that a pressure in the conduit fonned in the pressing plate is properly adjusted. It is important that the capacity of the heat transmission of the steam, in other words, value of U is remarkably larger than that of the hot water.

Referring to FIG. 2 showing an embodiment of the device for carrying out the present invention, steam of comparatively low pressure is supplied to a heat medium conduit 2 formed in a pressingplate 1 from a steam supply pipe 3. The steam supplied to the conduit 2 imparts heat to the pressing plate while passing through the conduit 2 so that the temperature of the pressing plate 1 becomes a predetermined level. Steam pressure in the conduit 2 is indicated by a pressure gauge 4. An outlet of the conduit 2 is connected to a steam trap 7 through a conduit 14 and a valve 6 mounted on the conduit 14 and further connected to an inlet of a pump 10 through a valve 8 and a pressure gauge 9. A bypass conduit 11 is connected to the conduit 14 as shown in FOG. 2, and a valve 12 is mounted on the bypass conduit 11.

The method for heating the pressingplate of the continuous flat press utilizing the above-mentioned device ishereinafter illustrated. As a first step, valves 5 and 6 are closed and the valve 12 is opened. Next, the pump 10 is driven so that the partial pressure of air in the conduit 2 is decreased, until the air pressure becomes a predetermined value. Next, the valve 12 is closed and the valve 5 is opened so that steam is supplied into the conduit 2 while the pump is continuously driven and the

valves

6 and 8 are opened. in case the pressing plate 1 is heated at a temperature below 100 C., the inside pressure of the conduit 2 is maintained at a proper pressure below an atmospheric pressure. Since the supplied steam is condensed after imparting heat to the pressing plate 1, so that a drain liquid is produced inside the conduit 2, it is required to control the pressure in the conduit 14, as indicated at the pressure gauge 9 (hereinafter referred to as secondary pressure), so that the above-mentioned drain liquid can be discharged to the outside of the device through the steam trap 7. By our experimental tests, it was found that a primary pressure indicated by the pressure gauge 4 should be maintained at a pressure higher than a secondary pressure indicated by the pressure gauge 9 by at least 0.1 kg./cm. preferably 0.3 kg./cm. if the above-mentioned pressure difference is below 0.1 kg./cm. it is impossible to discharge the above-mentioned drain and to maintain the surface temperature of the pressing plate 1 in uniform condition. It is recommended to use a Nashtype water sealing pump, which is capable of discharging the drain, as a decompression pump for carrying out the present invention. By utilizing the above-mentioned decompression pump, the remaining partial pressure of air is completely removed during the discharging operation of the drain through the steam trap 7, even though the partial pressure of air still remains in the conduit 2 after completion of the first operation for decreasing the partial pressure of air. In the above-mentioned operation, the drain is discharged from the drain discharging outlet 15, while air or steam is discharged from the discharging outlet 13.

As mentioned above, in case of carrying out the pressing operation by the continuous flat press in a temperature condition below 100 C., the heating method of the invention is applied to a decompression steam-heating method. in spite of using a long meandering conduit having small cross-sectional diameter, since the conduit is heated uniformly by the adiabatic compression effect by the supplied steam, the temperature in the entire conduit within the pressing plate becomes uniform if the pressure in the conduit is maintained in uniform condition. Therefore, the distribution of temperature of the pressing plate becomes very uniform. Therefore, by applying the above-mentioned heating method, according to the present invention, a long pending problem with respect to the drawback of the conventional flat press, which is illustrated in the preamble of this specification, can be completely solved. Consequently, a uniform flat-pressing operation can be carried out with high efficiency for pressing the high-grade worsted fabrics and various fabrics which require the operation at a temperature below I00 C., by applying the heating method of the present invention.

What is claimed is:

1. An improved method of heating a pressing plate of a continuous flat press provided with at least one conduit formed therein for flowing a heating medium through said flat press, and provided with a steam trap having an input connected to said conduit, and of maintaining said pressing plate at a predetermined temperature below C., comprising the steps of discharging air from said conduit, supplying steam into said conduit, discharging said steam and drain liquid produced in said conduit from said conduit through said steam trap while maintaining the inside pressure of said conduit at a predetermined pressure below atmospheric pressure, and decreasing the pressure at an output of said steam trap to a pressure lower than said conduit pressure by at least 0.1 kg./cm. thereby maintaining said pressing plate at a uniform predetermined temperature.

2. An improved heating method as set forth in claim 1, in which said steam trap output pressure is decreased to a pressure lower than said con duit prssst re by at least 0.3 kg./cm.

Claims

1. An improved method of heating a pressing plate of a continuous flat press provided with at least one conduit formed therein for flowing a heating medium through said flat press, and provided with a steam trap having an input connected to said conduit, and of maintaining said pressing plate at a predetermined temperature below 100* C., comprising the steps of discharging air from said conduit, supplying steam into said conduit, discharging said steam and drain liquid produced in said conduit from said conduit through said steam trap while maintaining the inside pressure of said conduit at a predetermined pressure below atmospheric pressure, and decreasing the pressure at an output of said steam trap to a pressure lower than said conduit pressure by at least 0.1 kg./cm.2, thereby maintaining said pressing plate at a uniform predetermined temperature.

2. An improved heating method as set forth in claim 1, in which said steam trap output pressure is decreased to a pressure lower than said conduit pressure by at least 0.3 kg./cm.2.