US1624094A - Machine for and method of applying varnish to sheets of fibrous material - Google Patents

Description

Apriii i2 9 19270 L. T. FREDERECK- MACHINE FOR AND METHOD OF APPLYING VARNISH T0 SHEET-S OF FIBROUS MATERIAL Filed March 2', 1925 mm-shm 1 lamb A ril 12 1927.

p L. 'r. FREDERICK MACHINE FOR AND METHOD OF APPLYING VARNISH T0 SHEETS 0F F'IBROUS MATERIAL Filed March 2. 1925 2 Sheets-Sheet 2 jam Iozzzb ff rfiderz'ck 624m o Jj Patented Apr. 12, 1927.

UNITED STATES P 1,624,094 ATENT OFFICE.

I LOUIS T. FREDERICK. OF VALPARAISO, INDIANA, ASSIGNOR TO FIBROC INSULATION COMPANY, OF VALPARAISO, INDIANA, A CORPORATION OF INDIANA.

MACHINE FOR AND METHOD OF APPLYING VARNISH T0 SHEETS OF FIBROUS MATERIAL.

Application filed March 2, 1925. Serial No. 12,497.

It is well known that a composite material usable for silent gears. insulation and many other purposes is made by first impregnating sheets of paper or other fibrous material with a binder, then laying a pluralit of the impregnated sheets one upon anot ier and finally consolidating the whole by means of pressure usually accompanied by the action of heat. One of the well known binders employed is a synthetic resin or condensation product formed from phenol and formaldehyde and known as bakelite, this being a substance which hardens under heat and pressure.

It is common in impregnating the fibrous material to pass a strip of it through a bath of the liquid resin or varnish dissolved in alcohol or other solvent. These strips are many inches and sometimes several feet wide, and considerable difliculty has been found in distributing the binder uniformly across the width of the strip. It is found that when the strip is assed through a bath and then over a distributing roller the tendency is for the roller to remove more of the varnish from the ends than from the mid portion. The result is that the finished product is non-uniform and unsatisfactory. To remedy this manufacturers have resorted to the expedient of thinning the varnish by increasing the amount of solvent. By thus thinning the varnish it readily flows from the strip and the amount left on it is more uniform but this method has disadvantages because it is affected bv temperature, by the speed of the strip and by the amount of solvent contained in the varnish. Furthermore this method is expensive because the solvent is expensive and much of it is wasted by evaporating and assin off into the air. The object of my invention is to avoid these difficulties and to obtain a uniform distribution across the sheet without increasing the amount of solvent in the varnish. Generally speaking I attain this object by stretching the strip toward the mid portion, that is, by requiring the mid portion to pass over a stripper or wiper which is bowed at the mid portion, thus exerting greater pressure on the strip at the mid portion and consequently forcing from the mid portion the same amount as is forced from the marginal portions of the strip.

I accomplish my object in the manner and Figure 4 is a sectional detail on the line I 44 Figure 3.

Figure 5 is a vertical section through the bath on the line 55 Figure 3.

Figure dis a vertical section of the bath equipped with somewhat modified stripping and guiding means.

Figure 7 is a vertical section on the line 77 Figure 6.

Like numerals denote like parts throughout the several views.

Referring first to the form shown in Figures 1 to 5 inclusive, the dryer has a housing 1 which is heated in any suitable manner,

for example, by means of steam pipes 2.

The impregnated strip passes in through a port 4 shown at the right end of Figures 1 and 2, and emerges through a port 6 shown at the left end of Figures 1 and 2. Any suitable means may be provided for drawing the strip 8 through the machine. In the present case there is a roller 10 over which the strip passes'and a traction roller 12 located adjacent to it for pulling the strip through. The roller 10 is rotated by means of a worm gear 14 engaged by a worm 16 driven by cone pulleys 18 or other suitable source of ower.

greatly varied.

Referring now to the part of the mechanism which is more closely concerned with From the rollers 10 and 12 the strip passeson to astorage reel 19' guide plates 48 are associated with the second dipping roller to supportit and guide the strip through the machine. From the dipping roller 46 the strip rises to the stripping elements which servev to remove the surplus hinder from the fabric and which are of the essence of the invention.

In the design shown in Figures 3, 4 and the first stripping element 49 is in the form of a bar or rod which is arranged horizontally above the level of the liquid and is of a length somewhat greater than the width of the fabric. It is supported at the ends in a swinging frame which includes side plates 50 and a rigid cross bar 52. This frame is pivotally supported on the side guides 48 by means of bolts 54 and the construction is such that the weight of the frame and stripping element causes the latter to press against the fabric and strip the excess liquid from it. The stripping element is bowed at the center by means of a set screw 56 which screws in the cross bar 52 and at its inner end engages the mid portion of the stripping element. By rotating this screw inward towards the stripping element it may be caused to bow the latter to any desired degree of curvature.

From the first stripping element the fabric strip passes preferably to a second strip ping element 56 which is bowed upward against the strip so as to increase the pressure at the mid portion thereof as does the stripper 49. This element 56 is mounted in the side guides 48 and the degree of curvature is regulated by a set screw 58 mounted in a bracket 60.

In operation, when the mechanism shown at the left end of Figure 1 is functioning and drawing the strip through the machine the fabric passes from the supply roll 34 over the guide roll 40, thence beneath the dipping rolls 44, 46 and thence up to the stripping elements 49, 56. I am not positive as to the exact actionof the stripping elements, that is, whether they actually exert greater pressure at the mid portion of the strip or whether there is a natural tendency for the strip to bulge at-the mid portion and the stripper compensates for this and exerts uniform pressure. On the other hand it may be that capillary action tends to hold the liquid more tenaciously at the mid portion than at the marginal portion, but in any event I have found that the bowing of the stripper makes it possible to equalize the amount of varnish retained on the strip, and by changing the curvature of the stripper the distribution may be regulated and the amount of varnish remaining at the center may be increased or decreased at will.

As the strip leaves the final stripping element 56 it passes into the housing of the dryer where it becomes dry and from which it passes onto the receiving roll 19. It is then ready to be cut into sheets and consolidated in a bot press.

The strippers shown in Figures 3, 4 and 5 are non-rotary. Hence an appreciable amount of friction is generated. In some cases where a weak paper is to be impregnated it is desirable to reduce the amount of friction, and I accomplish this by the mechanism shown in Figure 6 in which all of the parts are the same as before except that instead of using the second fixed stripper or wiper 56 I substitute a stripper 62. This is in the form of a roller which bulges toward the center as best shown in Figure 7 This roller is rotatably supported upon gudgeons 64 journaled in side plates 66 which are analogous to the side plates 48 but have slots 68 in which the gudgeons may be seated. These slots are shown in dotted lines in the .upper left portion of Figure 6. This mechanism has the same general effect as before, the disadvantage from the structural standpoint, however, being that a somewhat heavier stripper element is necessary and it is not ad]ustable exce t in the sense that other rollers having di erent degrees of curvature ma be substituted.

It will be observe that the mechanism by which the varnish may be distributed is quite simple, being not very different from the ordinary guide rollers which have been commonly employed in dipping baths. I Curvature, however, has made it possible to gain a uniformityof distribution of the varnish, and this is of vital importance in producing a uniform product from the impregnated material. I

It will be understood, of course, that the number of bowed or curved strippers may be varied but I have found that two is usually the best number.

While I have shown non-rotary curved or bulged strippers in Figures 1 to 5 inclusive and a rotary curvedor bulged stripper in Figures 6 and 7, I do not herein claim the rotary one but do so in a companion application filed on the 2nd day of March, 1925, Serial No. 12,499.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is: p

1. The method of distributing liquid uniformly upon a fibrous sheet consisting in first applying an excessive amount of liquid to the sheet and then removing the surplus by manner,

subjecting the-*sheet to a stripping action in which theKcentra'I portion of the sheet is stretched to a greater extent than the marginal portionsthereof.

'2. The' met-hod of applying a binder to a fabric' i-n the form of a liquid consisting in first applying to the strip an excess of the binder in liquid form, then removing the excess by exerting in a'straight line across the strip from edge to edge and with a motion lengthwise of the strip, a pressure such as to cause the strip to bulge at the central portion.

3. The method of impregnating a strip of fibrous material consisting in first applying an excess of the liquid to the strip and then removing the excess by causing the strip to travel over a stationary element having a curvature such that the mid portion of the strip is required to travel a longer path thanthe marginal portions.

4:. The method of impregnating a strip of fibrous material wlth a binder consisting in passing the strip through a bath of the binder in liquid form, then pressing upon the strip in such manner as to cause a graduated bulge at the mid portion for uniform removal of the excess liquid, and then drying the strip.

5. In a machine for applying varnish to a fabric, means for applying an excessive amount of the varnish, and a curved stri per over which the Wetted strip passes, t e stripper being curved to cause the strip in passing to bulge at the center.

6. In a machine for applying varnish to a fabric, a bath for containing theliquid varnish, means for guiding a strip of the fabric through the bath, and a curved stripper over which the wetted strip passes after it has emerged from the liquid, the stripper being curved to cause the strip in passing to bulge at the center, and thus have the surplus varnish removed uniformly across the stri 7. Apparatus for impregnating a fa ric with varnish, the apparatus having a bath for applying'an excess quantity of the'varnish, a curved stripper-which bulges at the center, and means ifor causing a strip of the fabric to pass first through the bath and then over the stripper.

8. Apparatus for impregnating a fabricwith varnish, the apparatus having abath for applying an excess quantity otthe varnish, a curved stripper which bulges at the center, means for causing a strip of the fabric to pass first through the bath and then over the stripper, and means for drying the strip as itleaves the stripper.

9. In a machine for applying varnish to a fabric, a bath for containing the liquid varnish, means for guiding a strip of the fabric through the bath, and a stripper for removing the surplus liquid from the strip after it leaves the bath, said stripper being arranged crosswise of the.strip and being curved outward toward the strip at the mid portion, and means for yieldingly pressing said stripper a ainst the strip;

10. In a mac ine for applying varnish to a fabric, a bath for containing the liquid varnish, means for guiding a strip of the fabric through the bath, and a curved stripper over which the wetted stri passes after it has emerged from the liquid the stripper being curved to cause the strip in passing to bulge at the center, and being non-rotary for making sliding contact with the strip.

11. In a machine for applying varnish. to a fabric, a bath for containing the liquid varnish, means for guiding a strip of the fabric through the bath, and a stripperfor removing the surplus liquid from the strip after it leaves the bath, said stripper being arranged crosswise of the strip and being curved outward toward the strip at the mid portion, and means for yieldingly pressing said stripper against the strip, the stripper being non-rotary for making frictional contact with the strip as it passes.

In witness whereof, I have hereunto subscribed my name,

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