US1958984A - Means for coating and impregnating sheet material - Google Patents

Description

2 Sheets-Sheet 1 May15, 1934. c. J. BEAVER MEANS FR GOATING AND IMPREGrNIlG` SHEET MATERIAL Filed Feb. 25, 1932 INVENTOR ...By 9W, MIM f Y y ATTORNEYS May 15 1934- c. J. BEAVER 1,958,984

' MEANS Fon comme AND IMPREGNATING SHEET MATERIAL Fiwled Feb. 25,-1932 2 Sheets-sheet 2 ATTORN E YJ' Patented May 15, 1934 MEANS FOR COATING AND IMPBEGNATING SHEET MATERIAL CharleaJames Beaver, Bowden, England I Application February 25, In Great Britain 1932, Serial N0. 595,209 March 18, 1931 2 Claims. (C1. .Sil-55) `This invention relates to a processand apparatus for impregnating and/or coating sheet material (which is understood to include material in the form of narrow strips) in a continuous oper- 5 ation. Examples of the material treated are paper and textile fabrics. Examples of the impregnating and coating material are oil, insulating compounds, varnish and rubber solution. This material may be in a liquid or semi-liquid state. In U. S. Patent No. 1,752,972 I have described an apparatus for impregnating sheet material in which the latter is first dried in a chamber and is then passed through a tank disposed inside the drying chamber. 4From this tank the material is passed through an aperture in Aa second tank and into a body of liquid or semi-liquid material contained in the second tank. This latter tank is placed outside .the drying chamber and the liquid material in it seals the aperture as the sheet material is being passed through it. In this form of apparatus a comparatively large volunie of liquid material must be maintained in the apparatus. This may be disadvantageous in certain cases, for example, where the liquid material is subject to deterioration by the action of air and moisture. The larger the volume of liquid material in the apparatus, the higher will be its rate of deterioration for a given volume of liquid transferred to the sheet material. Further, the large tank inside the drying chamber necessitates a cor'- respondingly large drying chamber, requiring a large iioor space and increasing the costof the apparatus. The apparatus constructed in accordance with the present inventionr consists of a mod- `ined form of that described above, and I obtain thereby important economies both as regards initial and running costs. In this modiiied form I provide within the drying chamber a compartment which merely serves as a reservoir for the liquid escaping through the aperture in the impregnating and/or coating tank, the sheet material to-be treated being drawn through the drying chamber, over (and not into) the compartment in this chamber, and then being passed through the aperture into the body of liquid or semi-liquid material contained in the impregnating tank. In this apparatus the impregnating tank is placed outside the drying chamber andthe impregnating takes place solely in this tank, the pressure upon the liquid in this tank being, for this purpose, under a comparatively high pressure as compared with that in the drying chamber. ,As the compartment in the drying chamber has merely to collect the liquid escaping from the aperture, this can be made of relatively small dimensions, so that the capacity of the drying chamber may be correspondingly reduced. The impregnating tank can also be of comparatively small capacity, so that the total volume of treat- C3 ing liquid in this tank and in the compartment in the drying chamber can be considerably reduced as compared` with that required in the apparatus of my previous patent. This permits the rate of deterioration of the treating liquid also to be reduced for the reasons indicated above. The modified form of apparatus has also other ad-l vantages.

A pump generally will be used to return the liquid in the compartment in the drying chamber to the impregnating tank so as to maintain the liquid in this tank at an appropriate level.

One form of apparatus for carrying out the process according to the invention is illustrated by Way oi' example in the accompanying drawings, 75 whereim- Figure 1 is an end elevation of the apparatus, some parts being shown conventionally,

Figure 2 is a front elevation, and

Figure 3, a sectional elevation of a to a larger scale.

The apparatus comprises a tank 1 adapted to contain a rotatably mounted drum 2 of the material to be treated, and guide vrollers 3, 4, 5 and 6, rollers 4, 5 and 6 being electrically or otherwise 85 heated. .The tank l1 has a partition 'l stretching across it, forming a compartment 57, the purpose of which will be described in more detail later. A tank 8 of comparatively small dimensions is disposed above the tank 1 and is provided with guide 9o rollers 9 supported in frames 10. The tank 8 can be heated by a steam coil 11.

Referring to Figure 3. the bottom wall l2 of the tank 8 has anaperture 13 oi small'widthto permit the passage of the material being treated o5 from the tank 1 into the tank 8. When the material has been passed through the aperture, o indiarubber blocks 14 are adjusted so that they make contact terial. The blocks 14 extend across the and are secured to holdersv15. rIhe blocks are, brought into their proper positions by rotating screw-threaded spindles 16 supported in brackets 1'7, the spindles 16 engaging with blocks 22 secured to the holders 15. The blocks are clamped in position by'rotating box-nuts 18 which' are engaged by screw-threaded bolts 19. The nuts 18 have long handles 20 to facilitate their operation. The upper wall of the tank 1 has an aperture 2l arranged opposite to the aperture 18.

detail, drawn so a pairy i with the opposite sides oi the nia-f A vertical frame work 231 carries at its upper end a bracket 24 in which is mounted a shaft 25. 'I'his shaft carries a roller 26 and a pulley 27, drawn by a belt 29. 'I'he roller 26 rotates in a bath 28 of coating material. The framework 23 also supports brackets 30 to which is fixed two pairs of scrapers 31 adapted to be heated by steam coils 32. 'Ihe pairs of scrapers are arranged on opposite sides of the material as it travels from the tank 8 to the roller 26 for the purpose of removing excess liquid, with which the material has been impregnated and/or coated, in the tank 8. The material is led on to the roller 26 over a small guide roller 33, and on leaving the roller 26 it passes over a guide roller 34. After leaving .the latter, the material passes around a water-cooled roller 35 and is iinally coiled on to a winding-up drum 36.

The roller 35, a pulley 37 and a gear wheel 38 are all mounted on the same shaft 39, the latterbeing supported in a bracket 40. 'I'he drum 36 and a gear wheel 41 are mounted upon a shaft 42 supported in a bracket 43. The gear wheel 41 is frictionally .mounted on the shaft 42 to provide `for the increase in diameter as the material is wound up on the drum 36. driven by a chain 44 from a sprocket wheel 45 mounted on the shaft 42. The wheel 41 is driven from a wheel 46 through a pulley 47, the wheel 45 and pulley 47 both being mounted on a shaft 48. The tank 1 has an aperture 49 by means of which connection may be made to a vacuum pump 61. The compartment 57 formed by the partition 7 contains liquid or semi-liquid material which iiows through the apertures 13 and 21 shown in Figure 3 asv the material passes from the tank 1 into the tank 8. This liquid or semiliquid Amaterial is kept heated by coils 50 and is returned to the tank 8 by a. pump 51 which withdraws the liquid from the tank -1 through pipe 59 and delivers it to the lower part of the tank 8 through pipe 52.

Assuming that the apparatus is to be used for impregnating paper with insulating oil or compound for electric cables, a roll of the paper is inserted into the tank 1 after removing a cover 53. The paper 60 is then drawn over thevarious rollers, so that it takes the path indicated by the arrows in Figure 1, covers 54 and 55 being removed for this purpose, the cover 55 having an aperture for the passage of the paper. The rubber blocks 14 are then closed up to thepaper and fixed in position. 'I'he tank 8 and the compartment 57 may then be lled with the impregnated oil and the various covers replaced. The tank 1 is then placed under a high vacuum, by means y of the vacuum pump 61, to draw out gases and/or moisture from the paper, and the driving mechanism started to draw the paper through the apparatus. The drying of the paper is assisted by the heated rollers 4, 5 and 6. It will be seen that the paper does not pass into the oil in the compartment 57 but rst meets the il at the oil seal at the bottom of the tank 8. The latter is under atmospheric pressure while the tank 1 is under a very much lower pressure, and the impregnation of the paper takes place in the tank 8 under the impulsive uct-ion of the sudden increase in pressure. This type of impregnation is more efficient than that described in U. S. Patent No. 1,752,972. The guides in this tank ensure that the paper remains a sulciently long time in the oil to complete the impregnation process. During 'Ihe wheel 38 is,

the impregnation, the pump 51 delivers oil leaking through the seal from the tank 8 to the compartment 57, back to the tank 8, so that a'continuous circulation of the oil takes place. The heating coils 11 and 50 maintain the oil in a sufficiently iiuid condition. From the tank 8, the paper passes over the roller 26 rotating in the bath 28 containing wax or other suitable material. 'I'he paper is coated with this material as it passes over the roller 28, the coating material being kept in a moltencondition by suitable means such as by steam coils which may be connected at 58 (Figure 2). The paper then passes around the cooled roller 35 and is finally wound up on the roller 36.

It will be seen from the above description that the compartment 57 merely serves as a reservoir for the liquid escaping from the tank 8, and that the sheet material does not pass into the liquid in the compartment 57 but is drawn over this, the whole of the impregnation taking place in the tank 8. Some of the advantages obtained by this construction have been already indicated. In addition to these, the reduction in capacity of the drying chamber permits a higher order of vacuum and hence more efficient drying conditions to be maintained for a given vacuum pump, and less heat energy is required to maintain a given temperature as compared with the apparatus described in our prior patent. Also the path of the sheet material through the machine may be made a comparatively short one, and due to the more efficient drying and impregnation, the material can be drawn through the apparatus at a greater speed for a given thickness of material and degree of impregnation.

What I claim as my invention and desire to secure by Letters Patent is:- Y

1. An apparatus for the continuous impregnation of sheet material, comprising a drying chamber, an impregnating tank disposed outside the drying chamber and having an aperture in its wall communicating with the drying chamber, a reservoir disposed inside the drying chamber and arranged solely to receive liquid escaping through the aperture in the impregnating tank, guiding devices for the sheet material, disposed inside the drying chamber and so arranged that the material passes over but not into the reservoir, means for drawing the material over the guiding devices .in the drying chamber and through the aperature in the impregnating tank into a body of liquid therein, and means for placing the drying chamber under a comparatively low pressure as compared with that in the impregnating tank.

2. An apparatus for the continuous impregnanation of sheet material, comprising a drying chamber, an impregnating tank disposed outside the drying chamber and having an aperture in its wall communicating with the drying' chamber, a reservoir disposed inside the drying chamber and arranged solely to receive liquid escaping through the aperture in the impregnating tank, guiding devices for the sheet material, disposed inside the drying chamber andl so arranged that the material passes over but not into the reservoir, means for drawing the material over the guiding devices in the drying chamber and through the aperture in the impregnating tank into a body of liquid therein, and means for differential of pressure between tank andthe drying chamber.

CHARLES JAMES BEAVER.

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