US2139314A - Process for manufacturing gaskets - Google Patents

Description

Dec.6,1938.' 4 NmGL'EsB-Y 2,139,3 4;

PROCESS FOR MANUFACTURING GASKETS Original Filed Nov. 2, 1934 Ugleaya Patented Dec. 6, 1938 PATENT OFFICE PROCESS FOR MANUFACTURING GASKETS Nicholas Ewing Oglesby, Troy, N. Y., assignor to Bohr-Manning Corporation, Troy, N. Y., a corporation of Massachusetts Application November 2, 1934, Serial No. 751,235 Renewed April 1, 1938 9 Claims.

which are not used in the gaskets, may be returned to the beaters of the paper making machine and re-used. This method results in a saving in the quantity of fiber used, and also a saving in consumption of chemicals in the saturating bath.

It is a further object of the invention to produce, as a new article of manufacture, a saturated paper gasket which is characterized by the absence of changes in shape upon changes in moisture content which may result from changes in the humidity of the atmosphere.

It is old in the art to make an asbestos gasket, brake lining, or clutch facing by first cutting a blank from a sheet of asbestos and then impregnating the blank with a non-hygroscopicbinder. Thereafter the portions of the sheet not used are returned to the beaters of 'the sheet forming machine. Thus, the idea of pre-cutting a fibrous sheet, impregnating the out portions, and reusing the remaining portions is old, in its broadest aspects. In the past, however, it has been impossible to apply such method to the production of saturated paper gaskets because of the fact that paper changes materially in size (expands or contracts) when saturated, whereas asbestos sheets do not. Thus, if blanks were cut from conventional gasket making paper and then saturated, the size and shape of the blanks would change materially, due to saturation. For instance, if a circular, ring-shaped blank were cut from the usual gasket making paper, and then saturated with one of the usual saturants, and

cured, the blank would be found to be elliptical in,

shape, changed in size, and commercially useless.

In accordance with the present invention, it is a possible to determine ahead of time exactly what changes in size and/ or shape may be expected in the blank when the same is subjected to saturation, and, consequently, allowance can be made for these changes, and the blank cut accordingly, so that the final saturated article will be exactly the desired size and shape.

Thus, substantial economies in themani1facture of saturated paper gaskets can be effected, because the blanks may be cut from the sheet prior to saturation, and the portions of the sheet not used can be returned directly to the beaters of the paper making machines. These economies extend not only to a saving in paper fibre, but also to a substantial saving in the material used for saturating.

In the manufacture of saturated paper gaskets it has been common practice to make-the paper from rope, jute, wood fibre and the like, or from these fibres mixed with comminuted cork. Such papers have been saturated with a solution of glue and glycerine. The glue has been tanned, and the web dried. Finally gaskets are out in various shapes from the dried web. Two principal disadvantages follow from such prior art methods. In the first place it is wasteful of paper fibre and saturating materials, because as high as fifty per cent of the saturated web is usually wasted. Secondly, if the saturation is not very complete, a perfect seal will not be formed around the edges of the gasket.

When the conventional methods are used, it has not been found practical to re-use the waste resulting from cutting the gaskets, because the waste cannot be returned directly to the beaters of the paper making machine, but must be subjected to a cooking process to remove the saturant. and the expense of the cooking process has increased the cost of recovering the paper fibres to a point where it has not been economical.

In accordance with my process, no chemicals are present in the sheet when the waste material is cut therefrom, and consequently none of the saturant is lost. All of the waste paper, after cutting, is in a form that can be returned directly to the beater without any preliminary treatment,

so that it may be immediately disintegrated and re-run at a nominal cost.

The essentials of my process are (1) controlling and measuring the expansion and contraction characteristics of the desired sheet of paper.

which result from saturating and impregnating the sheet with the desired saturating solution; (2) computing beforehand the change in dimension which will result when a blank of predetermined size is saturated; (3) cutting the gasket in accordance with such computation and allowing for the change in dimension which will result from the saturation; (4) saturating the cut blank in the desired saturant; (5) permitting the blank to expand or contract to the desired dimension, .(6) drying the completed gasket. types of saturants are used, a tanning or fixing step may be employed before the final drying. The terms saturating and impregnating are When certain used throughout the specification and claims in a generic sense to cover the incorporation of a suitable amount of a saturating or impregnating agent in the body of the paper, as distinguished from mere surface painting or coating.

Another important feature of the present invention is the use of special papers in the manufacture of saturated paper gaskets. I have found that gasket paper as heretofore made for saturating is not suitable for my process, if close tolerances in the final gasket are required. Paper as used in the past for the manufacture of gaskets has the fibres oriented predominently parallel to the length or machine direction of the paper. Such papers have a high length and relatively low cross strength. When saturated, fixed, and dried, such papers expand and contract predominantly in the cross direction, the change in the length direction being relatively small, either on expansion or contraction. If circular gaskets arecut from such paper, they will become elliptica'l when saturated, and will remain elliptical after drying.

Another defect of saturated gaskets made from conventional paper in accordance with prior art processes is that they expand and contract unevenly in the two directions with changes in moisture content resulting from changes in humidity. An important aspect of the present invention relates to my discovery that saturating papers having a cross strength to length strength ratio of about 1, expand and contract approximately equally in both directions, both in the saturating operation and. when exposed to varying humidities. In paper of this type, the fibres have a random orientation, in which about equal numbers of fibres are parallel to the length and cross directions.

I have conducted numerous tests with many samples of paper of different types, and I have found that, as the cross and length strengths approach equality, the cross and length expansioncontraction characteristics of the sheet also approach equality. Furthermore, the ratio of cross to length dimensional change resulting from satu'ration is substantially equal to the ratio of cross to length dimensional change resulting from changes in moisture content, which may result from humidity changes.

My experiments show that, with commercial saturating paper, such as is conventionally used, the increase in cross dimension resulting from saturation varies from about 1% to 1 a change which is equivalent to approximately 1 inches per 100 inches of dimension in the gasket material. .On 24 inch gaskets, this would be equivalent to .36 inch along the cross direction 01' the paper. With such paper, the change in the length, or machine direction, is negligible, and in fact, with some papers, there is a slight shrinkage in that direction. It is obvious that a precut circular gasket would therefore become an ellipse after saturation and it would be difiicult to allow for the expansion in one direction and the contraction or lack of change in the other direction. Even if such an allowance could be correctly made, and a circular gasket produced, changes in dimension resulting from changes in the humidity of the atmosphere would always be unequal in the two directions, and it would, therefore, be impossible to maintain the circular form of the gasket under varying conditions of humidity. The same difliculties apply to any desired regular shape of gasket, and the circular form is used in this specification merely as a convenient illustration.

For close tolerances a paper stock is desired which has substantially the same properties in both length and cross directions. Such a paper may be made on a hand sheet machine, and the fibres may be so laid down that they have a substantially equal resultant orientation in all directions. For certain special uses, but not for gaskets, papers of this type have been made with a special cross-flow vat. With these new and special machines, such as a Sonbert machine of the general type shown in United States Patent No. 1,924,154, it is possible to obtain approximately the same tensile strength in the length and cross directions of the paper, or, in fact, in all directions. As stated above, I have found that a paper with these characteristics expands and contracts substantially the same in all directions when subjected to saturation with the solutions disclosed below, and also when exposed to variable conditions of humidity, and that such paper is, therefore, highly satisfactory for my process. This is true whether the paper is made from rope, jute, wood, or a mixture of these fibres, either with or without the addition of comminuted cork. Likewise, many other fibres may be used.

When a properly balanced sheet is made on a special machine so as to give a cross to length strength ratio of about 1 to 1', itis found that the cross strength is appreciably stronger than the cross strength of regular papers heretofore used and that the length strength is lower than the length strength of regular paper as used in the past. In the case of gaskets, however, the requirement for strength is the same in all directions and the gasket is, on the whole, no stronger than its weakest portion. For this reason, a gasket with equal strengths in all directions is preferred to the ordinary gasket.

.Not only is there an advantage in the overall strength in using special paper for my process, but when the gaskets are first cut and then saturated, the edges of the gasket are more completely filled and saturated, which minimizes the chance of leakage, especially since in many cases, the paper has not heretofore been completely filled with the saturating material.

The following is an illustration of the way in which my invention may be carried out: A roll of saturating gasket paper of the thickness required to produce the desired gauge of gasket, is first tested for its expansion characteristics when saturated. As an example, we will take a paper with a cross to length tensile strength'ratio of roughly, 1 to 1. Out of this paper, a circle or disc 24 inches in diameter is out. Pencil lines are drawn on two diameters,-one-parallel and one perpendicular to the machine direction. This circle is saturated with the impregnating solution by first floatingon the solution until the solution penetrates through and then submerging, removing from the solution and scraping the excess solution from the surfaces by the sharp straight edge of a steel bar, A suitable saturating solution is bone glue (32 millipoises) 1 part, glycerine 3 parts and water 7 parts, and a suitable temperature is 130 F. The saturated circle is cooled or allowed to cool until jelling takes place after which it is submerged in a solution of 1 part commercial formaldehyde to 9 parts water at a temperature of 40 F., removed, allowed to dry or dried slowly and brought to equilibrium case of paper as indicated, the two diameters will have increased substantially the same, for example, .12" or .5%. Assuming that it is desired to cuta circular gasket 20 in outside diameter with a 1" face, i. e., 18-" inside diameter, we will pre-cut from the paper an outside diameter of X:

or 100.5X=2000 The inside diameter will be Y:

x or 100.5Y=1800 In this case, the raw paper stock is cut into circular paper rings of 19.90" outside diameter and 17.91" inside diameter.

The rings so cut from the raw paper stock are next saturated, scraped, cooled, and cured in substantially the manner described above with reference to the disc, using substantially the same solution.

The operations may be carried out by hand as described for the test circle of paper, or the operation may be carried out continuously on suitable equipment. For instance, it has been found very satisfactory to practieethe method of my invention, by using a machine such as the one shown diagrammatically in the accompanying drawing, although many other types of machines may be employed with equal success.

In the accompanying drawing:

Figure l is a diagrammatic vertical sectional view of a portion of a machine adapted to carry out my process;

Figure 2 is a similar view of another portion of the apparatus, and

Figure 3 is a similar view of still another portion of the apparatus.

Referring to Figure 1, a plurality. of rolls 5 are shown carrying a flexible wire belt 6 through a tank 1 containing a solution 8 which may consist of the ingredients mentioned'above, namely,

-a refrigerating chamber submersion, if this method of operation is -preferred for any particular type of gasket. From the wire belt 6, gaskets are dumped upon a cloth belt II which is carried by rolls l2 through rubber calender rolls l3, where the excess of the impregnating solution is squeezed from the surface of the gaskets ill. Such solution flows into the box l4, from which it may be pumped or otherwise conveyed back to the tank I. From the belt II, and after passing through the calender rolls I3, the gaskets are dumped onto a second wire belt 15, carried by rolls l6.

Referring to Figure 2 the belt I5 is a continuation of that shown in Figure l, and in addition to the rolls E6, the belt is supported by a third roll H. The gaskets, after being dumped from the belt ID to the belt l5, are carried thereby through 18, the latter being cooled by any suitable commercial refrigerator installation. A desirable temperature range within the refrigerator I8 is between 34 and 38 F., a temperature. low enough to cool but not low enough to freeze the water in the saturating solution contained in the gaskets l0. From the belt I5 the gaskets are dumped upon another flexible wire belt l9 carried by rolls 20 and passed under idler rolls 2|, and the gaskets are fixed by the solution 22 in the tank 23. A suitable fixing solution is 1 part commercial formaldehyde to 9 parts of water and a suitable temperature is 40 F. From the flexible wire belt IS, the gaskets are dumped upon a third belt 24, a fragmentary portion of which is shown in Figure 2.

Referring to Figure 3, the gaskets are dumped upon the belt 24 carried by rolls 25, and the belt extends into a drying chamber 26. At the end of the travel of belt 24, the gaskets are dropped upon another belt 21 within the drying chamber, trained about rolls 2B. The gaskets are conveyed by the last-mentioned belt lengthwise of the drying chamber and outwardly therefrom. They may be deposited into any suitable container 29 after their complete travel through the drying chamber. The chamber 26 should be kept at a suitable temperature, preferably not in excess of 90 F., a good range being between and Many well known methods of heating the chamber may be used, but it is preferred to circulate heated air therethrough, discarding part of the circulated air and adding new warm air to keep the humidity range between '30 to 40%. The humidity range may, however, be varied within wide limits, depending upon the rate of drying desired.

In the past both cylinder and Fourdrinier papers have been used for saturation to form gaskets. As a general proposition, the cross to length tensile strength ratio of Fourdrinier paper has been higher than that of cylinder paper. That this was true was purely an accidental difference of the two types of paper making machines. While the ratio has been somewhat more favorable with Fourdrinier machines, cylinder machines have been more extensively used, since the cylinder type paper machines form gasket material with h gher tensile strengths and since it is easier to make the thicker gauges of matetion is relatively less with thethicker gauges, since V combing is an action occurring primarily at the surface just after the fibres are deposited. Likewise the cylinders are run at lower speeds in making the thicker gauges and this also reduces the combing action. In no case of either cylinder or Fourdrinier paper has the cross to length tensile strength ratio exceeded .80 and it has only been on rare occasions that either the thicker gauges of cylinder paper or the Fourdrinier papers had a cross to length tensile strength ratio as high as .65. Since this condition has existed in the prior art it follows that while some of the prior papers are much better than others, none of them approach the ideal condition of a cross to length strength ratio of l to 1.

Where cross to length tensile strength ratio is used in these specifications, it should be understood that this ratio is obtained by dividing the cross tensile strength by the length tensile strength. The length direction is what is known as the machine direction. The cross tensile strength is obtained by testing 1" strips of paper cut perpendicular to the machine direction. The length tensile is obtained by testing 1" strips which are cut parallel to the machine direction. All tests are made at a relative humidity of 65% and a temperature of 70 F., after the paper has been conditioned at this humidity and temperature for at least two hours. A paper testing machine, motor driven, such as a Scott machine, is used. At least three samples are used for each determination. The testing machine is motor driven. The distance between jaws of the testing machine is 5", and the speed of travel of the testing machine is from '7 to 8 inches per minute. Samples that break in the jaws of the testing machine should be rejected. Results used as cross and length tensile strengths, respectively, are the average of three tests in each case.

It should also be understood that where the term cylinder paper is used, the paper may be -formed on one cylinder to produce a one ply cylinder paper, or on two or more cylinders to produce a multiple ply cylinder paper.

I claim:

1. The process of making gaskets of predetermined size and shape from paperlike material including cellulosic fibres in amount which will cause the paper to change dimensions upon saturation, comprising determining the dimensional change characteristics of the paperlike material upon saturation with a binder solution which swells cellulose, forming a blank from said paperlike material having a dimensional area and shape such that after saturation with such a binder and bringing to equilibrium with average atmospheric conditions the gasket will assume a desired size and shape, saturating the said blank with such a binder and causing expansion of the cellulosic fibres and change in the dimensional area of the formed blank and whereby the body portion and edges of the blank are saturated, and bringing the saturated gasket to conditions of equilibrium with average atmospheric conditions.

2. The process of making gaskets of predetermined size and shape from paperlike material including cellulosic fibres in amount which will cause the paper to change dimensions upon saturation, comprising determining the dimensional change characteristics of the paperlike material upon saturation with an aqueous binder solution, iorming a blank from said paperlike material having a dimensional area and shape such that after saturation with said binder and drying, the gasket will assume a desired size and shape, saturating the said blank with said binder and causing expansion of the cellulosic fibres and change in the dimensional area of the formed blank and whereby the body portion and edges of the blank are saturated, and drying the saturated gasket.

3. The process of making gaskets of predetermined size and shape from paperlike material including cellulosic fibres in amount which will cause the paper to change dimensions upon saturation, comprising determining the dimensional change characteristics of the paperlike material upon saturation with a glutinous binder solution which swells cellulose, forming a blank from said paperlike material having a dimensional area and shape such that after saturation with said binder and bringing to equilibrium with average atmospheric conditions, the gasket will assume a desired size and shape, saturating the said blank with said binder and causing expansion of the cellulosic ,fibres and change in the dimensional area of the formed blank and whereby the body portion and edges of the blank are saturated, and bringing the saturated gasket to conditions of equilibrium with average atmospheric conditions.

4. The process of making gaskets of predetermined size and shape from paperlike material including cellulosic fibres in amount which will cause the paper to change dimensions upon saturation, comprising determining the dimensional change characteristics of the paperlike material upon saturation with a binder of glue and glycerine which swells cellulose, forming a blank from said paperlike material having a dimensional area and shape such that after saturation with said binder and bringing to equilibrium with average atmospheric conditions, the gasket will assume a desired size and shape, saturating the said blank with said binder and causing expansion of the cellulosic fibres and change in the dimensional area of the formed blank and whereby the body portion and edges of the blank are saturated, and bringing the saturated gasket to conditions of equilibrium with average atmospheric conditions.

5. The process of .making gaskets of predetermined size and shape from paperlike material including cellulosic fibres in amount which will cause the paper to change dimensions upon saturation, comprising determining the dimensional change characteristics of the paperlike material upon saturation with a binder of glue, glycerine and water which swells cellulose, forming a blank from said paperlike material having a dimensional area and shape such that after saturation with said binder and bringing to equilibrium with average atmospheric conditions, the gasket will assume a desired size and shape, saturating the said blank with said binder and causing expansion of the cellulosic fibres and change in the dimensional area of the formed blank and whereby the body portion and edges or the blank are saturated, and bringing the saturated gasket to conditions of equilibrium with average atmospheric conditions.

6. The process of making gaskets of predetermined size and shape from paperlike material including cellulosic fibres in amount which will cause the paper to change dimensions upon saturation, comprising determining the dimensional change characteristics of the paperlike material upon saturation with a binder solution which swells cellulose, cutting a blank from said paperlike material having a dimensional area and shape such that after saturation with said binder and bringing to equilibrium with average atmospheric conditions, the gasket will assume a desired size and shape, saturating the pre-cut blank with said binder and causing expansion of the cellulosic fibres and change in the dimensional. area of the formed blank and whereby the body portion and edges of the blank are saturated, and bringing the saturated gasket to conditions of equilibrium with average atmospheric conditions.

7. The process of making gaskets of predetermined size and shape from paperlike material having a cross to length strength ratio of 0.80 to 1 and including cellulosic fibres in amount which will cause the paper to change dimensions upon saturation with a binder solution which swells cellulose, comprising forming a blank from said paperlike material having a dimensional 76 area and shape such that after saturation with such a binder, the saturated gasket will have substantially the same shape as the blank but will be of a different size, saturating the blank with such a binder and causing expansion of the cellulosic fibres and change in the size of the formed blank, and whereby the body portion and edges of the blank are saturated, and bringing the saturated gasket to conditions of equilibrium with average atmospheric conditions.

8. The process of making gaskets of predetermined size and shape from paperlike material including cellulosic fibres in amount which will cause the paper to change dimensions upon saturation, comprising determining the dimensional change characteristics of the paperlike material upon saturation with a binder solution which changes the dimensions of the material, forming a blank from said paperlike material having a dimensional area and shape such that after saturation with such a binder and bringing to equilibrium with average atmospheric conditions the gasket will assume a desired size and shape, saturating the said blank with such a binder and causing change in the dimensional area of the formed blank and whereby the body portion and edges of the blank are saturated, and bringing the saturated gasket to conditions of equilibrium with average atmospheric conditions.

9. The process of making gaskets of predetermined size and shape from paperlike material including cellulosic fibres in amount which will cause the paper to change dimensions upon saturation, comprising determining the dimensional change characteristics of the paperlike material upon saturation with a binder solution which shrinks the material, forming a blank from said paperlike material having a dimensional area and shape such that after saturation with such a binder and bringing to equilibrium with average atmospheric conditions the gasket will assume a desired size and shape, saturating the said blank with such a binder and causing shrinkage in the dimensional area of the'formed blank and whereby the body portion and edges of the blank are saturated, and bringing the saturated gasket to conditions of equilibrium with average atmospheric conditions.

NICHOLAS EWING OGLESBY.

Images