US2026765A - Molding process and molded article - Google Patents

Description

Jan. 7, 1936. w. H. WOODFORD 2,026,765

MOLDING PROCESS AND MOLDED ARTICLE Filed July 25, 1932 FIG. I

Fig. 5

INVENTOR.

' WATSON H.WoouFoRu ATTORNEY Patented Jan. 7, 1936 I UNITED STATES MOLDING PROCESS AND MOLDED ARTICLE Watson H. Woodford, Bridgeport, Conn., assignor to Remington Arms Company, Inc., a corporation of Delaware Application July 23, 1932, Serial No. 624,325

20 Claims.

This invention relates to the molding of articles from fibrous pulp, and will be described with particular reference to wads for shot shells, although its novelty and utility are not limited to these particular articles.

Shot shell wads are of at least three distinct types, each type serving a particular purpose in the shot shell. The bas'e" wad, which is a wad of very substantial thickness in comparison with its diameter, is provided with a central aperture and pressed into the base of, the shell opposite the metallic head thereof and between such head and the battery cup. Its primary function is to effect a seal between the interior of the shell and the joint between shell body and head, thereby preventing the escape of powder gases. A suitable charge of powder is placed upon the base wad, and upon the powder is located an overpowder wad usually of a type of paper of a thickness of the order of 6" to A". The over-powder wad is comparatively dense and non-resilient. Upon the over-powder wad are placed one or more filler wads usually of some type of hair felt. These wads are much more resilient than the over-powder wad and are designed to be pressed into close engagement with the bore of the shot gun, thereby effectually preventing the escape of powder gases around their peripheries into the shot charge. The edges of the filler wads are lubricated with such a substance as stearine, chiefly for the purpose of providing a lubricated surface on the gun bore and preventing abrasion of the shot and consequent leading of the bore. The lubricant must substantially penetrate the periphery of the wad, in order to prevent its complete removal in the cone of choke bored barrels, and consequent leading beyond this point.

The present invention is directed primarily to filler wads, although it likewise contemplates over-powder wads and base wads of essentially the same construction and made by processes substantially similar to those practiced in the pro duction of filler wads.

One object of the present invention is to provide a process for the individual molding of shot shell wads from asuspension of the wad forming materials in a fluid medium.

A further object of the invention is to control the characteristics and quality of the wads by suitable regulation of the concentration of the wad forming materials in. the fluid medium.

A further object contemplates the development of, a process of wad forming which includes the utilization of large quantities of scrap material resulting from the manufacture of filler wads as hitherto practiced.

The invention further contemplates the accurate control of the density and other physical characteristics of wads by the accurate regulation of the quantity of material entering into each wad.

The invention further contemplates wads and other articles molded from materials of a fibrous character in such a manner as to prevent the lay- 1 ing of, the fibres in plane substantially parallel to the wad surfaces and the consequent tendency of the wads to split into thin sheets.

The invention further contemplates wads having an improved capacity for absorbing a lubricant-and retaining such lubricant under temperatures above its melting point.

With these and other objects in view the invention consists in the novel articles and methods of their production to be hereinafter more fully described.

In the drawing:

Fig. 1 is a fragmentary sectional elevation of one form of apparatus used in the practice of the novel processes of the present invention. This showing of the apparatus is somewhat diagrammatic.

Fig. 2 is a fragmentary sectional elevation, partly in section, of a part of the apparatus shown in Fig. 1, positioned beneath the wad forming compression plungers.

Fig. 3 is a view similar to Fig. 2, showing the wad in the mold after compression by the plunger.

Fig. 4 is a fragmentary sectional'elevation of a mold and plunger adapted to produce an aper- 5 tured wad.

Fig. 5 is a perspective of a filler wad.

Fig. 6 is a perspective of an apertured wad as formed in the mold shown in Fig. 4.

Fig. 7 is a fragmentary side elevation of a 40 slightly modified form of mold charging tube and adjacent part of the mold.

Fig. 8 is a sectional elevation of a wad produced by the apparatus of Fig. 'l.

The wad forming materials utilized in the present invention may be any suitable granular or fibrous materials capable of suspension in water or other suitable fiuid medium. Preferably, the wad forming composition is a mixture of a relatively coarse fibrous material, such as hair, with a relatively fine and partially hydrated material, preferably wood pulp; and a somewhat granular filler material, such as sawdust. Any of these materials, or mixtures of any two or all three of them, in varying percentages produce wads of excellent properties for one or more of the three purposes hereinbefore mentioned. A suitable composition for filler wads comprises hair in proportions varying between 40% and 90%, sawdust in an amount of 10% to 25%, and wood pulp in an mount of to 100%. The hair may be derived from scrap felt, a large amount of such scrap resulting from the cutting of hair felt wads from large sheets. Approximately 35% of such sheets is scrap, and it'has been found impracticable to rework this scrap into other sheets. The wood pulp may be either sulphite pulp stock or scrap news print paper.

A typical composition for filler wads comprises 20% sawdust, 60% scrap felt, and 20% newspaper or sulphite pulp.

A typical composition for over-powder wads comprises 20% scrap felt or other fibre, such as jute fibre, 40% sawdust, and 40% newspaper.

A typical base wad comprises about 40% sawdust and 60% newspaper or sulphite pulp.

The process for forming wads from such materials as follows:

The scrap felt and news print paper or sulphite pulp, being properly disintegrated, are introduced with the desired amount of sawdust into a suitable tank or container a part of which is identified by the numeral in Fig. 1. The sulphite pulp or newspaper is disintegrated by mechanical working to a suflicient extent, but not to a point where it loses its fibrous character or the individual fibres become highly hydrated or gelatinous. It is essential that the fibrous character of the pulp be maintained in order to avoid such a cohesion between the fibres as would result in a rigid, non-resilient article. The suspension of the wad materials in the tank is maintained at a fairly low concentration, and is agitated by suitable means to maintain all portions thereof at the desired concentration. Concentrations up to 10% are permissible, but a concentration of the order of 1% is preferable.

Suitable means are provided for withdrawing measured portions of the suspension of wad forming materials from the tank and introducing them into a wad forming mold. For this purpose, the tank may be provided with any desired number of tubes H extending through the bottom of the tank and upward to a, point well above the top of the pulp suspension, indicated by dotted line l2. Surrounding each tube II is a measuring cup l3 of suitable construction and connected with suitable devices for its elevation from the position within the pulp suspension, shown in full lines in Fig. 1, to a position adjacent ,the top of the tube II, as shown in-dotted lines in Fig. 1. As each cup 13 is elevated to the dotted line position its contents are discharged into the tube I I and fall through said tube and a suitable connecting tube or sleeve l4 into a mold l5. Each mold I5 is fixed in a dial plate It supported above and closely adjacent to a fixed bed plate H.

For the production of wads of the order of A" to 'in thickness, mold l5 preferably has a height of about 3". Both ends of the mold wall are solid, while its intermediate portion is provided with suitably proportioned drainage perforations or slots 20. Each connecting sleeve i4 is arranged to fit inside of its associated mold l5 and to be drawn slowly upwardly as the pulp suspension settles in the mold. The time occupied in withdrawing the sleeves l4 varies from 2 to 5 seconds, depending on the particular composition used.

Each mold l5 when in position to receive :1.

charge of wad forming materials through the tube II is aligned with a perforated bushing l8 in the bed plate H. The perforations l9 of said bushing provide a vertical drainage for the pulp suspension fluid, while the slots 20 of the mold l5'providealateral drainage. i

The sleeve I4 is provided primarily for the purpose of preventing the escape of too large a quantity of the pulp forming material through the slots 20 before it has had an opportunity to settle, and said sleeve l4 iswithdrawn at such a rate that only a very small quantity of the pulp escapes through or enters the slots 20. i

The charge for a typical wad comprises 80 c. c. of the pulp suspension, which consists of substantially '79 c. c. of water and 1 c. c. of pulp. Before and during the withdrawal of the sleeve I4 about 10 c. c. of the fluid escapes through the bottom drainage perforations I9 and about 59 c. c. escapes through the lateral drainage perforations or slots 20. Of the remaining 10 c. c. of fluid, 9 c. c. is expelled in the pressing operation which will now be described.

The molds I5 being thus charged with accurately measured quantities of wad forming pulp, the dial plate 16 is indexed to a position in which the molds l5 are positioned beneath a set of wad forming plungers 2| (Fig. 2). again, aligned with perforated bushings in the .bed plate, l1, which bushings are substantially similar to the bushings I8 already mentioned. The plungers 2| are now lowered, compressing the pulp and expelling about 90% of the remaining fluid through both the drainage slots 20 and the apertures IS, the downward movement of c the plungers being stopped at a distance from the bottom of the molds corresponding to the desired thickness of the wad. If desired, an upward vertical drainage, as'well as a downward vertical drainage, may be provided by the use of perforations 22 in the heads of plungers 2|, as clearly shown in Fig. 3.

It has been found that the combination of lateral drainage through the slots 20 with downward vertical drainage through the bottom apertures l9 and, if desired, an upward vertical drainage through the apertures 22, is effective to prevent the laying of the fibres in planes parallel to the wad surfaces, and the resultant lamination or cleavage along such planes which characterizes practically all products hitherto made from molded fibrous pulp. The paper wads hitherto used, particularly as over-powder wads, are very highly laminated and upon firing of the shell they split into thin sheets which scatter about, obscuring-the shooter's view of the results of the shot. A similar characteristic is possessed by all prior articles of molded fibrous pulp. While solid articles have been molded from pulp which has been beaten and hydrated to such an extent that thefibres are disintegrated or gelatinized until their fibrous character is lost and under compression they adhere and form' a substantially rigid, non-resilient and non-fibrous article, the

present invention is believed to constitute the first process of molding fibrous articles of substantial thickness showing no cleavage. This result moreover is secured without the use of any binder whatever. Ordinary hair felt wads contain a very substantial percentage of a binder, yet the wads of this invention, with no binder at all, show a far greater resistance to tearing parallel to their faces than hair felt wads containing large quantities of binder.

Apparently three factors are involved in the The molds l5 are securing of wads of substantial thickness which are resilient, porous enough to take a lubricant,

and show no cleavage or lamination parallel to,

their faces. The first factor is the presence of a substantial amount of granular, material,- of which sawdust has been given as an example. It is a familiar fact in the manufacture of paper and pulp articles generally that in the formation of laying of the fibres which results in transverse cleavage is the large and controlled lateral drainage. Only about 25% of the fluid escapes through the face of the wad, and of this about half is pressed out after the wad material has become so concentrated as to prevent free movement of the fibres. The remaining 75% or more of the fluid escapes through the lateral drainage apertures; thus, the fibres tend strongly to be aligned in a direction perpendicular to the wad faces and directly across the usual planes of cleavage.

The third factor is the application of pressure to the wad faces. A large portion of the fibres being arranged substantially perpendicular to the wad faces, this pressure is applied to'them endwise, and results in diagonal displacement, curling and crinkling, which completes their felting into such a tangled mass as to prevent any tendency to cleavage.

A wad having concaved faces, as illustrated in Fig. 8, may be formed by introducing the charge of pulp suspension into the mold 15 in such a way that it acquires a whirling motion, and removing the sleeve while the suspension is still in motion. One means of accomplishing this result is illustrated in Fig. 7 in which the opening from the tube ll into sleeve I4 is adjacent one wall of said sleeve. The pulp of the suspension settles while it is being urged outwardly by the centrifugal action of the whirling suspension, and a wad with concaved faces results even though a fiat faced punch 2| and a fiat drainage bushing I8 of the type shown in Figs. 2 and 3 are used. Other desired shapes of wads may be secured by suitably forming the pulp engaging face of the plunger and/or the face of the drainage bushings l8.

An apertured wad (Fig. 6) suitable for or to be subsequently shaped into a base wad, may be made by the use, in the mold l5, of a suitable core 24, shown in Fig. 4 as supported in the sleeve It by a spider 23. Said core, however, may be supported in any other convenient manner, and if desired a corresponding projection may be formed on the wad compressing plunger 2| to better preserve the aperture formed by the core.

The wads having been compressed to the desired thickness, as heretofore described, the plungers 2| are withdrawn and the dial plate 16 is again indexed to bring the molds I5 over apertures in the bed plate. ll through which the wads are removed from the molds by suitable knock-out punches. The wads are subsequently dried under normal atmospheric conditions to remove the remaining moisture, and their edges are subsequently lubricated with a suitable lubricant such as stearine or petrolatum. It has been found that such pulp wads have the capacity for retaining the necessary amount of such lubricant at temperaturesat which the lubricant becomes quite fluid, whereas ordinary hair felt wads do not under these conditions retain the lubricant. Such a loss of lubricant from the edges of felt wads has in the past been the cause of many complaints of poor combustion of powder. Under summer storage conditions the wad lubricant becomes quite fluid and may work past the over-powder wad and into the powder charge with a resulting injury thereto. The wads of this invention will retain indefinitely a much greater quantity of lubricant than is necessary for the purposes hereinbefore explained, at temperatures substantially above the highest temperatures of storage conditions. Moreover, the invention offers for the first time a practicable means of accurately controlling the thickness, density and rigidity of wads. It is quite impracticable to manufacture sheets of felt or other material which are of uniform thickness, different parts of the sheets substantially vary in thickness, and the wads cut therefrom varyaccordingly. invention an accurately measured quantity of material enters into each wad and this quantity of material is pressed to a predetermined thickness. Greater uniformity in ballistics of shells, as well as superior lubrication and the absence of deterioration due to the escape of lubricant, are thus secured.

The embodiments of the invention and the processes herein are typical and illustrative only, the invention being susceptible to practice in other ways and by means of other apparatus,

all falling within the scope of the appended claims. Y

What is claimed is: I

l. The method of making a shot shell wad which comprises the placing of a measured by an imperforate sleeve during charging, the

withdrawal of said sleeve as the wad forming material settles in said mold, and the subsequent compression of said materials to form a wad.

3. The method of making a wad having a thick peripheral flange and .a thin center which comprises charging a measured quantity of a suspension of wad forming materials into a mold in such a manner as to cause'the suspension to revolve in said mold.

4. The method of making a wad having a thick peripheral flange and a thin center which comprises charging" a measured quantity of a suspension of iorming materials into a mold in such a manner as to cause the suspension to revolve insaid mold, and subsequently compressing said material under a die.

5. The methodof making shot shell wads which comprises the charging of a measured quantity of a suspension of the wad forming materials into a mold arranged for lateral drainage and containing an imperforate shield, and the withdraw- Under the practice of the present form a non-laminated article of subst'antial thickmass which comprises the charging of a measured quantity of a pulp'sus'pension' into a mold p'r o vided with later'al and vertical drainage apertures, and the shielding of the vertic'al drainag'e apertures during the charging operation A l 7. In thejmanufacture of shot shell wads, the method which comprises molding from a fluid suspension of a mixture of fibrous and granular materials, and varying the amount oflateral drainage during the molding operation, 8. In the manufacture of shot shell wads, the

method which comprises molding from a fluid suspension of fibre containing material under fixed axial drainage andvariable lateral drainage. 9. In the manufacture of shot shell wads, the method which comprises molding from a fluid suspension of a mixture of long fibres, short fibres. and a granular material, under fixed drainage in one direction and variable drainage in another direction. I

10.'In.the manufacture of shot shell wads, the method which comprises molding from a'fiuid suspension of a mixture of fibrous materials and a granular filler material under conditions or fixed axial drainage and a lateral drainage controlled to enable partial settling of the suspended materials prior to exposure to lateral drainage.

11. In the manufacture of shot shell wads fconn prising fibrous materials, the method of felting the fibres into a resilient, coherent,'unlaminated structure which comprises molding a fluid suspension of said fibrous materials and a granular material while providing a fixed drainage in one direction and controlling drainage in another direction so as to permit partial settling of the suspended materials before draining in said seconddirection.

12. In the manufacture of shot shell wads com prising fibrous materials, the method of felting the fibres into a resilient, coherent, unlaminated structure which comprises molding a fluid suspension of said fibrous materials and a granular material while providing a fixed drainage in one direction and controlling drainage in another direction so as to permit partial settling of the suspended materials before draining in said second direction, the amount of controlled drainage substantially exceeding the amount of fixed drainagd '13. In the manufacture of shotshell wads comprising 'fibrousrnaterials, the ineth'odfof felting the fibres into a resilient, coherent; unlam'inated structure which comprises'molding a fluid susmold" during the settling" of the charge, releasing the supernatant liquid "laterally from saidrnold,-, 1 and compressing the charge. v

v 15. In the manufacture of shot she'll wads ',"the method which comprises introducing into :a mold aicharge of a fluid suspension of a mixture of fibrous and granularmaterials, allowing a settling of said charge in said mold,ireleasing' the supernatant liquid laterally from saidmold, and compressing the charge. i" v 16. In the individual moldingof shot shell 'wads, the methodwhich comprises the addition to a, fluid suspension of fib're'sf of from 10% to 40% of sawdust, and the molding of the fib'er sawdust mixture into shot shell wads which are coherent inuse.

17. A coherent gun wad molded from a waterlaid mass of .a fibrous mixture including hair, wood pulp and sawdust, theisawdust constituting 10% to 40%. of the wad according to its intended use.

18. A coherent gun wad molded from a waterlaid massvof a fiber mixture including hair, Wood pulp and, sawdust, wherein the fibrous content varies'from 45% upward and the sawdust content varies froin 10% to 40% according to the 40 intended use. of thewad. i I

' 19. A coherent gun wad molded from a waterlaid mass of a fiber mixture including hair, wood pulp and sa'wdust, in the following proportions"? 20. A coherent gun wad-molded from a waterlaid mass of a mixture of a fibrous materialv and sawdust, the sawdust being present in an amount between 10% and depending upon themtended use of thewad.

hair, 20% to 90%; wood pulp, 10% to 60%; sawwA'rsoN H. WOODFORD.

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