US1858193A - Manufacture of leather - Google Patents

Description

May 10, 1932.

c. G. SHAW 1,858,193

MANUFACTURE OF LEATHER Filed Feb. 9, 1929 2 SheetS-Shee l May 10, 1932. C. G. SHAW 1,858,193

MANUFACTURE OF LEATHER Filed Feb. 9, 1929 2Sheets-Shee. 2

- -3- IEE/vm? El Hft-555g@ Patented May 10, 1932 UNI-iran STATES CHARLES GEORGE SHAW, OF HUNTSVLLEONTARIO; CANAZDAv MANUFACTURE OFALEATHER'.;

Applicationledlebruaryy, 1929.. SeriaLlYNo.: 338,876.

This invention relates to improvements'in* the manufacture Vof, leatheri with' morel Vpar# tlcular reference to the'simiiltaiieou's compact-v ing and finishing ofpieces of leather, such as' 6'- vegetable tanned .sole leather in' pieces such sides, crops, bends, shoulders'andbellies,. or any pieces of leatherofisubstantial area. as produced atthe tannery, andthezob'ject of: the invention is to devise animproved inethod 10 or process of simultaneously finishing and compacting such pieces ofv leather tota'de-V sired degree of4 compact-ness A as'may" be re'- quired for any of the various,commercial uses. which improved process results inav `iinished product' of superior' quality, linish and 'value to that produced by methods here'-v tofore used.

In the manufactureof vegetable'tannedsole leather there 'are various classication's, botlr as to tannagg'ev and .rmness Various vegetable extracts as for instancequebracho', chesti nut oak, cuteh and such like, aswell 'asfliquors ma de from oak, hemlock and' Wattle barlrkan-d'f 5 the other vegetable substances, as nuts, shells 2 tanned, or union tanned'.l Leather'- of this classification the World' Vover vhas onequality, which is imparted largely'by compacting pressure, that quality vis: `known among'the trade on this continent as firmness and is desitenated throughout British countriesu'sually. use of such terms as, solid, very solidy and such like are used in the tannage of'I leather and .leather tanned outright` by' the use of these materials is calledby various trade'names such as vegetable'tanned, orfoakI leatuer. but the Vfactiremains that'rough or,

pressures usedin the compactingand dancing slipper ory a. lumbermans caullred sole. It is forthe compactmgand'iinishingV of'vegetabletanned leather inA particular that this improved 'process has been devisedfal though its application' in' timeto come Will lilrely be more-varied. This improved process is `not intended'for use in: the manufacture of i' o comparatively uncomp'acted leather, such .as the soi calledI flexible chrome retanned. Neither `will it `be of much' advantage to `use the extremely high vunit..pressuresxas in this improvediprocess 'frthenishing of chrome 60 ormineral sole leather, ,a as theirmness of these tannages'isimparted as-desired Aonly by changing` th'enature.of;the lill-ing material, as bythe addition of ceresinvvax, resin, or other hardfwaxto th'el'paraftin base material With' Which '.they are Ausually-f` impregnated. The use of Ipressesin the manufacture of chrome. sole leather-cis for-"the'epurposeA of obtaining a 'tin'ished'lor emh'ossedgrain or flesh surface, which may 'bedone at pressures of a' few hundred pounds tortheY square 'inch of' surface, andis `notru'sedffcmthe compaction ofthe leather asis they case in the lmanufacture of Yvegetable tanned sole leatherbymy process. Furthermore," the faulty' finish hitherto s0 obtainedv on chrome'sole leather-could not be; tolera'tedion the'vegetable tanned Asole leather. l'litherto it has been" common practice to fini shfand compact "vegetable" sole leather in rollingmachines; by'means lof rolls, usually' of the pendulum type Vor its equivalent. such as flat"bedrollers,` which rolls are usually, as in America, of comparatively small size although some, asin Great Britain, are of largersize and diameter, but'all rolling machines Contact at anyone time only lwith a very` restricted `portionio'fthesurface of the leather andin-'compacting a piece ofleather of suby stantialareafinthis Way the pieceis moved with respect tothe roller anditsbed so as to eventually' cause the roller to Work over the entire surface ofthepiece. `When leatheris thus compacted"by^rollers there is a marked tendency to laterally distend the piece and thus unduly thin it: This is'not the casein my process, as by exertinga pureI squeezing pressure simultaneously over a substantially large area, the surface area, is not .increased and therefore the sheet isV not unduly, thinned: Further, When leather is thus rolled due to the lateral distention tendency and the limited area in contact with the roller at any time, the tendency of the fibres to assume the normal (bowed) position in which they grew on the animal, and which is a source of constant trouble and expense to the tanner in the making of a desirably fiat piece of leather' is aggravated, which is not the case in my process, which produces a desirable sheet-flat piece of leather compacted and finished to any desired degree with the greatest possible ease and in one operation and without the necessity or desirability of rolling.

In France and some other European countries leather has been and is being compacted by hammering which has some advantages, but has not come into use in America and Great Britain due to a great many disadvantages, chief of which are the tediousness and labor cost of the operation and the lack of surface finish produced.

Of the many -disadvantages contingent upon rolling the following may be considered among the most important:

First. Portions of some hides such as cowhide and Indian buffalo hide hips are badly and unavoidably bagged, or cupped. Likewise for instance the rolling of a heavy finders bend invariably dishes it which is undesirable. These faults as before mentioned, which are aggravated in the rolling process, by my process are corrected and eliminated. In the compacting and finishing by my process of hundreds of thousands of pieces of leather from almost every variety of hide as tanned for sole leather, the percentage which have not been finished with absolute ease to a sheet-like fiatness is absolutely negligible.

Practically all rolled leather in pieces as Vbends and crops have a certain amount of dish consequent upon its faulty finishing and compacting. This may be partially removed by prolonged storage in properly built piles, but he fact remains that the majority of leather as shipped from the tannery is baggy. Chief among many objections to baggy leather are:

A. The difficulty with which it is handled in a dieing out machine while being cut for soles, etc. There have no doubt been hundreds of fingers and thumbs lostby the operators of these machines, which losses might be -directly traceable to baggy leather. Leather finished by my process lies on the block of a dieing out machine sheet-like in its fiatness and allows an operator every possible freedom in the placing of his dies. This one p-oint alone has in at least one cut sole establishment to my knowledge when cutting sheet-fiat leather as produced by my process as against a rolled finished leather', increased the efficiency of the dieing out machines and operators by at least twenty-five percent. Further the dies rest normally in a level position in cutting sheet-flat leather and do not slide so as to injure the finish or grain when the sole is stamped out and the operator has no reasonable excuse for dragging his die7 or for damaging the grain as is often the case when cutting baggy leather.

B. Baggy rolled finished leather when stripped as for a Knox sole cutting machine causes many of the finest quality strips to be wider across the center than across the ends or podded. This results in unevenness in the length of soles cut from these strips, or as is usually done prior to cutting the strips into soles, an evening strip is cut from the strip. These trimming strips are called whip lashes in the trade and are wasted. In any case this unevenness in the strips or soles cut from baggy leather is very undesirable and wasteful. Sheet-flat leather as produced by my process is admirably suited for this method of cutting as podded strips are eliminated and the soles produced are of even length and the waste of leather for this reason eliminated.

C. Baggy, rolled finished leather does not bales to the greatest possible compactness and effects valuable saving yin the cost of ocean transport.

Second. When branded leather is rolled. the roller in passing over the lump brand, bumps and hammers upon it and makes this part very horny and hard, aggravating the unevenness in texture of these parts. Also rolling does not leave the grain surface of these branded areas level and flat. Further, rolling tends frequently to crinkle the branded area and the lumpy parts are forced in a quite haphazard and uncontrollable manner to appear when finished on either or both the grain or flesh side of the piece; all of which makes the skiving or other subsequent corrective measure very difficult and in many cases impossible to perform. In my process the grain surface is always smooth and fiat with the lumps always on the flesh side and all of the disadvantages consequent upon rolling these parts substantially eliminated.

rlhird. The surface finish as obtained on rolled leather leaves much to be desired as is well known among the trade. a mirror like surface and polish may with the greatest ease be obtained over the whole grain surface of a piece of leather, such as any bend, and the leather may be compacted to any desired degree, all without any rolling, or other finishing process whatever in the space of twenty seconds in one or two strokes of a single machine requiring at this present state of its development only one man to feed the apparatus with leather, and press the button. and another to take it away.

By my process nssssiosi It is, oficourse, reasonable that the leather should have been previously setout inthe normal manner and-coarsefgrained orwWrin-` kled leather should .be previously j aeked, and 1 moisture content which may be done in any suitable Well known Way.

Fourth. In all rolling machines there is a.V decided tendency toiexert less pressure on thin portions than on the thicker portions ot' a piece. For'instance, alarga proportion of sole leather bends are thinner, over those areas or parts adjacent to the edges Where. the shoulder and belly have been Icut ofi and these thinnerv portions are Aalmost invariably of'looseriibres than the thicker portions, and require more` pressure tosuitably compact them. By the use of my process this fault is very easily correctedbecause they lie at the edges-and these thin parts may be given pressures greatly in excess of those applied to otherA portions, so that avery desirable uniform coinpactnessand feel is given to the Whole piece. This is'accomplished as hereinafter more fully explained,y

lVith the iiattening, rmiiigand general iniproveinentin appearanceand quality as the` object, the pressing of sole leather in pieces such as crops and bends as-a suppleF nient to rolliiiglias been tried and has been found ot' very questionable value due:

Firstly to the variationsin thickness -in a piece ot leather and inequalities such as Vbrands and to thel lack ot acushion or othersuitable means of properly distributingthe pressures -over the thicker Vand thinner portions oia thefpiece-iii a uniform manner.

Secondi Y to the Oreat lack ot suticientlv l es .i

high-total pressuresA and to the inadequacy of the apparatus employed to produce them..-

Thirdly to the glaring miscalculation or the lackot knowledge and the apparent sregard of the intensity ot pressures necessary V'to accomplish the intended results.

Fourthly to the apparent ignorance ofthe fact thatwvlien leather is once substantially compacted,` as in'rolling, the fibres become' set together and atremendous increase in 'unit pressure;` over the unit pressure used in the rolling is required in a subsequent p ing operation to remore or correct the consequent upon or aggravated bythe rf and these extremely high unit pre siires Wernever obtained and properly .dis i These above mentioned tour reasons are illustrative only of many reasons for the practical failure to produce the results claimed of thisoperation as a supplement to rolling yand it must here be stated that any apparaacked.

tus .hitherto known in-the solev leather'iiidustryris so inadequate for the carrying out ofmy process as to be absurd.

In the above mentioned process of first compacting by rolling and subsequent pressing of sole leather pieces such as are produced at the tannery, no claim such as the one Which I non make and claim as my invention had hitherto to my knowledge been made, that leather of suitable tannage for the use it is intended, such as vegetable tanned soleV leather in pieces such as bends or crops, may simultaneously be compacted and finished by a pure `pressing process in av single machine to any compactness or firmness as requiredV by the sole leather trade and this Without the necessity or desirability or use of rolling, which is entirely eliminated, or any other compacting or finishing operation. Furthermore, the leather as produced by my im proved process is superior in substantially every respect to like leather Finished by any other process hitherto devised. Furthermore, the increased cutting value and supe rior iinish of leather produced by my process is at once apparent and may readily be Vappraised, and my claim as to the increased value ot the product readily substantiatedv and secondary only to this superior value ofthe product are the advantages ot increased efficiency of the apparatus resulting in the use ot fewer machines for compacting purposes, as the rollers may beentirely eliminated, and each machine is of much greater output capacity which results in asavifnginA machines.

Furthermore, the operators for myfprocess need not be highly skilled as is the case in rolling and any intelligent laborer can be taught to operate the apparatus to capacity production in a very short time. v

rThere is also by the use of this process a very susbtantial reduction in labor costs eiiected.- rlhis in the majority oitanneries may reasonably be expected to amount to titty percent ot the labor costs involved by their present method of compacting. In some tanneries Where greatcareis taken in finishing and the sole leather is rolled tivo orv three times this saving might be much greater. It isof course impossible to make a positive statement in this respect.

.Furthermore pigmented iilms or dressing ot such a .nature as to not successtullywithstand the action ot'a rolling machine may to great advantage be applied to the leather While the grain is open tibred and absorbent and in such a. state as is commonly found'in sole leather tanneries, atthat stage ot' the process Where it is dry after having been oiled the second time and set out and preferably These iilms 4may be of a Waterprooic ses the grain side before pressing and this leather' A is beautifully compacted and finished by this purely pressing process without the necessity or desirability of rolling or any other process Whatever, and any degree of compactness desired may be obtained in such leather by the use of my process.

The invention consists in the improved process, all as hereinafter more particularly described. The fundamental intrinsic principle involved is the application of sufficiently high intensities of pressure applied simultaneously over the whole or at least a substantial area of a piece of leather in a 'purely squeezing and compaeting manner, to force the whole or at least a substantial portion of the piece of leather of suoli dimensions and nature as previously explained, to assume a sheet-like flatness as desired and to exert these sufliciently intense pressures properly distributed, by any suitable apparatus, over the whole of the piece or that substantial part thereof which lies within the apparatus, and a sufliciently high total pressure applied. simultaneously to meet the requirements of the high unit pressures which are necessary to force the previously substantially uncompacted leather fibres to become compacted by this squeezing force Vto any desired degree as required for marketable sole leather, of any firmness desired; and that during this operation the fibres are so moulded and set by these sufhciently high unit pressures that the piece of leather remains sheet-flat upon its removal from the apparatus. Furthermore vby use of an improved apparatus in the nature of a pad or cushion as described hereinafter and in my co-pending application, all irregularities in thickness, and humps, as brands and as found in ordinary marketable sole leather are successfully coped with, and

do not cause serious concentrations of pressure on these thicker portions of a piece. As a result of the successful distribution of pressure over the whole surface of the piece, the grain surface of the leather which when quite plastic and which when pressed against the iiat mirror-like surface, ireferably chromium plated, of the wearing plate acquires during lthe compact-.ing process the facsimile of the lpolished surface against which it is pressed.

This finish is more easily obtained by properly conditioning the grain as with water or any other suitable Wash or dressing prior to pressing.

Likewise the flesh side acquires a very pleasing and marketable appearance from its contact with the smooth spring steel or other top sheet of the pad. Mention has been herein made of the desirability of applying higher unit pressures on thin, loose iibred portions of the leather than on thicker, firmer iibred portions adjacent to them. This may be accomplished most readily by the use of what I have termed a balanced anvil block as illustrated in Fig. 3 in conjunction with the improved pad, which are more fully described in my co-pending application.

This improved process may be successfully carried out in any press of suiicient capacity, platen size, and strength by a proper adjustment of the pad for the control of edge pressures, as by perforating some of the rubber sheets in a suitable manner and adjusting the thickness of the pad by adding a sufcient number of layers of rubber and steel to give ample cushioning action; but the balanced anvil block is of great assistance in relieving the pad of unnecessary work and the press of unnecessary side strains and it should be used. By the use of such an anvil block with a suitable pad upon its surface as in my copending application, suitably graded intensities of pressure may be exerted over the whole surface of the piece of leather such as an ordinary bend as follows.

Assume that the dimension of the top surface of the pad and anvil block are 42 inches wide and 7 2 inches long, and the bend to be pressed is 24 inches wide and 50 inches long and thinner along the belly edge than the back edge and likewise thinner at the shoulder than at the butt end; due to the balancing action of the anvil block any straight line drawn across the top surface of the pad and through the center point, such as center or diagonal lines, will divide the total imposed load acording to the laws of leverage such lines acting as fulcra.

Assume that such a bend is placed lengthwise on the surface of the pad so that its center rests upon the center of the pad, then as the press closes the anvil block which is free to align itself, tilts slightly upward on that side upon which the belly side of the bend rests and likewise at that end upon which the shoulder end of the bend rests, really a sort of diagonal t-ilt. In this manner any tendency of a piece of leather to be thicker at one edge than the opposite edge is in a general way compensated for and during the first stages of the squeeze. All other irregularities in the thickness of the piece are compensated for by the action of the pad, and the bend is thus uniformly pressed with uniformity of intensity of pressure all over its whole surface area.

lf, however, the bend is placed lengthwise on the platen as before and moved endwise so that the shoulder edge of the bend is closer to the crosswise center line of the pad than the butt edge then the crosswise center line of the pad does not equally divide either the area or the length of the bend which lies on either side of it, and with the crosswise center line of the pad acting as fulcrum, the butt part has theadvantage'of both greater length and area than the shoulder part, and by closing the press and exerting the desired total squeezing pressure on the bend as so placed, that part of the total load which is imposed on the butt part will he less than that part ot the total load which is imposed on the shoulder part.

Furthermore, theshoulder part being both ot lesser length and-area and having imposed upon it a greater portion ot the total load thanthe butt portion will consequently receive much higher intensities ot pressures distributed overl its smaller area thanare distributed over the larger butt area by the lesser portion of the total load andthe desired degree of coinpactness both in the shoulder and the butt parts attained.

Thus by t-he use of my process ina manner similar to thatl just described and as ina press capable ot exerting from six to ten squeezes per minute, each of ve thousand tons or as desired, which speeds and tonnages are readily obtainable, by placing a crop in two or three differing positions on the surface of the pad and by the use or" two or three strokes of the press, which strokes may be of Varying tonnage as desired, the simultaneous finishing and compacting of a sheet-flat sole or other leather crop may be accomplished with great iinesse and dispatch, and without the necessity or the desirability of rolling.

As before mentioned the s desirability ot' having the leather reasonably smooth. and tree from folds before pressing may be readily understood.

The general appearance, feel and finish of sheet-flat sole leather as finished byimyl process is Very superior and may easily be obtained thoughout the whole range ci varieties as on the market, turn-sole leather requiring pressures from about two thousand pounds to about thirty-tive hundred pounds to the square inch of grain surface area under pressure. Ordinary manufacturer"s leather or leather generally suitable tor Goodyear sewing requiring 'from about iiyethousand to perhaps seven thousand pounds. Firm finishes as tor iinders bends requiring from about six thousand pounds to perhaps ten thousand pounds per square inch, although this last figure may be a somewhat low limit and for finishing the extremely hard and iirm tannages, such as ai admirably suited for caulked soles for river drivers use' in the lumber industry, pressures oit 'from Fifteen thousand to about twenty-tive thousand pounds per square inch may be advantageousy employed. The pressure employed for the espective varieties may Vary considerably 1om those noted above, due to `Variations in ie type of hide, and the tannage, but these ressures are substantially accurate. It deired, suitable mechanism mal :be provided whereby this whole range otpressure is connur@ :de

Veniently and instantly under thewcontrol ot the operator. For instance, in the apparatus now in use :tor carrying-,out my process ,this is .accomplished by the press-ingfotan electric control button whichshutsithe valve supplyused and the unit pressures employed-.dur-

ing its pressing -an astonishing vVariety of finishes may be rproduced, from thesame tanot leather.

As betorelmentioned these results are not possible ot attainment by any apparatus hitherto -lnown or used' in the -leather industry. The apparatus at present `useid in my process is capable of exerting in onesqueeze atotal squeezing pressure of over six thousand nine hundred tons, sixtimes penminute and 1 of properly'distributing this high total pressure as may bedesirable, and any intensity of pressure up to and even. in excess oi twenty thousandpounds persquare inch may be success- Jfullyapplied as may be desirable to obtain-any degree et compactness required inftheproduct and thus Velinfiinating.-entirelyfthe .proc-- ess of rolling.

in accompanying drawings is shown anapparatus `suitable for carrying out the improved-process, which .apparatus is similar to that describedin my co-.pendi-ng application.

ln the drawings,

Figure 1 is fa diagrammatic sectional elevation of a press suitable torlcarryingfout the. improved process.

,Figure 2 is a diagrammatic. sectionall elevation showing a step in theprocess,.the apparatus illustrated in this iig-uref being 'slightly modified trom that illustrated in lFigure l.

Figure 3 is adiagrammaticsectional'elevation of al modiiied form oi apparatusdn which the pad A is supported uponfwhat; may be termed a balanced. anvilblockfand in this View is shown a central lengthwise section of an m'dinaryl steer hide bend.

Figure 4 isa detached View ot-thefbend shown in Fig. 3.

In the drawings like characters offreference indicate corresponding parts in .the-Vari yous gures.

- 1n the apparat/usas illustrated, thestatione leather, and the dressing whiclimay ary head platen of an hydraulic press of suitable strength and capacity is indicated by the numeral 10 and the anvil block or moving platen of the press by the numeral 11 which should preferably, but not necessarily be constructed so as to readily align itself while pressing a piece of leather of wedge shaped cross section such as a stag bend or shoulder and which feature I have called the balanced anvil block as in my co-pending application.

A indicates a special form of laminated pad suitable for carrying out my process which pad is composed of layers 12 of spring steel or rawhide alternating with layers 13 of rubber or rubber composition and the layers 13 may, if desired, be provided with perforations 14.- or other irregularities of section and the thickness of the layers 12 and 13 of the pad would preferably be of progressively decreasing thickness from the bottom to the top of the pad.

A wearing plate 15 having a suitable surface finish is carried by the head platen 10 and may, if desired, be formed with means for heating the plate such as the steam passages 16.

A piece of leather being operated upon is shown in position within the press by the numeral 17, the piece being so placed that the flesh side thereof contacts with the pad A while the grain side is uppermost so as to come in contact with the wearing plate 15.

In Figure 2, the leather piece 17 which is in position and being pressed is shown as having a blemish or brand mark 18 which causes a hump on the flesh side and this will be later referred to. Also in Figure 2 the perforations have been omitted from the pad A.

In finishing leather according to the improved process the leather piece 17, after it has been so treated that it contains the proper humidity content, which may be done in any suitable well known way, is placed upon the pad A with the grain side uppermost and the piece is then subjected to pressure within the press and in this pressing operation the piece is subjected to a pure pressing action without the desirability or necessity of previous or subsequent rolling and pressures of from 2000 pounds per square inch of leather surface upwardly to practically any desired pressure may be successfully employed, which pressures may be very greatly in excess of pressure which could be used when compacting by `f rolling.

The most important feature of the process is that all or Vat least a substantial area of the leather piece is subjected simultaneously to a pure pressing operation wherein unit pressures of sufficient intensity are properly distributed Over the area under pressure and thus not only is a desirably uniform compactness obtained throughout the area of the piece but the piece is forced to assume sheetlike flatness and as the fibres are compacted and set in this position by the high pres'-` sures employed the sheet remains fiat on its removal from the; press.

A further very important feature of the improved process is that blemishes such as brand marks, indicated at 18 in Figure 2, may be successfully coped with and when a piece containing a hump 18 caused by a brand mark is being pressed this hump will cause a depression in the upper layers of the cushion pad A so that the compacting of the piece at the hump will be comparatively uniform with that throughout the remainder of the piece and when the piece is 11emoved from the press this hump may be so conveniently skived oft' from the flesh side so that the blemish so far as is humanly possible may be removed, which makes this blemished portion much less undesirable.

If desired, the wearing plate 15 may he heated, as illustrated in Figure 1, and by this means a more perfect finish may he obtained on the grain side as there is a tendency when the grain side of the leather is warmed while under pressure to soften the leather on this surface so that it tends to iow and the result is a more perfect finish.

Referring to Fig. 8 of the drawings, this shows the provision of a balanced anvil block 19 which is provided with a spherical bearing 20 seating in a spherical set 21 in the platen 11. The pad A is supported upon the anvil block 19 and is positioned thereon so that the center of curvature of the spherical seat is at or near the center of th top surface of the pad and therefore the anvil block and with it the pad is capable of a tilting movement upon the platen 11 in which movement the center point of the top surface of the pad does not move.

In Fig. 8 a steer hide bend 22 is shown i lengthwise section being pressed within the press. rIhis bend is of varying thickness, the shoulder portion B being thinner and of looser fibre structure than the kidney portion C. Also the butt tip D may be either thicker or thinner than the portion C.

If a uniform compactness and firmness is to be produced in the fini-shed bend it is necessary that the unit pressures over the area of the bend be so distributed nat the loose iibred portions be subjected to a greater intensity of unit pressure than the closer ibred portions and this distribution of unitpressure must be accomplished regardless of the thickness of the respective portions of the bend.

This desirable distribution ofvunit pressures is facilitated by the use of the balanced anvil block 19.

In placing a bend 22 in the apparatus shown in Fig. 3, the operator predetermines those portions of the bend which are to be` subjected to greatest and least unit pressures and by properly positioning the'bend on the surface ofthe pad Awith respect to the ccntre point thereof When the squeeze is exerted, the anvil block and With it the pad will tilt and due to the principle of levers functioning .ith the centre point of the top surface of the pad as fulcrum the distribution of unit pressures over the surface of the bend will vary, depending upon the disposition and characteristics of the various local curves of the bend With respect to the centre point of the top surface of the pad.

In this Way, by suitably placing the bend above described,the total load imposed upon the bend may be divided with respect to any straight line passing through the centre point of the top surface of the pad so that by the use of the balanced anvil block described and the resilient pad A the total load is distributed as desired.

From the above it Will be apparent that by suitably positioning a bend in the appa ratus an infinite variety of loading concitions may be obtained vv'herebf,7 practically any desirable distribution of the total load may be effected to produce the results desired in the finished article.

Y its preiuouslv stated, in carrying out the improved process, unit pressures greatly in excess of those possible in rolling may be readily employed so that greater compactness in the finished product may be obtained, and due to absence of spreading, the thickness of the finished piece is not merely as seriously afe fected, the unit pressure used depending upon the degree of compactness, firmness or hardnessfof the leather desired in the finished product.

lt will be understood that by compacting or .compactness is meant the stiffening effect called inthe trade firmness which firmness has reference to the resilience or resistance to bending. like a sheet of thin spring metal, and also to the ease With which it may be cut, seivn or otherwise Worked in a shoe factory. Also, substantially uncompacted leather, means leather not sufficiently compacted or firmly or properly finished to be termed linished sole leather.

ln the foregoing specification and appended claims. the term vegetable tanned sole leather means sole leather in the tannage of which the chief tanningagent is an extractor liquor of vegetable origin containing tannin, or any blend of tanning materials as are commonly known to the trade, and Which leather when analyzed in accordance with the official method rof the American Leather Chemists Association is shown to contain tannin.

ils the sheet-like fiatness of the leather as produced by this process is one of its great advantages, in the carrying out of this process, in order to facilitate the Vattainment of this sheetflikelflatness, A such machines as .may be lused in preliminary operations ony the leather should bev such as `Will `have a` smoothening effecten the lea-ther, such as a jack or setting out machine, Without firming the leather, as

kopposed to machines Which have .la decided `not onlythatleather ofthe characterindin cated may be compacted in flat condition by high pressures exerted.simultaneously over a. substantial-area butJ that tilting of theadjoining faces of a press may be takenadvantage of tovary the pressure upon different parts of the leather so that a heavier pressure can be exerted upon a relatively small area,l the moment of pressure upon any unit area of the leather .With refernce to the tiltingaxis of the face of the anvil being made equal tothe moment of the pressure upon any other unit area. l believe myself also to be the first to provide any effective interaction between the press and the lea-ther to assist in making this V100 selective variation in pressure most useful by tiltably mounting (here spherically mounting) one of the platens of my press.

lt Will be evident that the spherical mounting, as distinguished from mere pivotal mounting, makes the platen adj ust automatically about any line through the face of the platen or its adjoining pad and not merely through a single basis line.

lt will be further evident that the placing 1 of the tilting or center close to the surface of the leather being compacted, substantially eliminates lateral movement of `the leather during its compaction notvvithstandA ing that the movable platen may re-adjust its position after conipacting has begun.

lt Will further be evident that the selective variance in they pressure above does not in the least interfere with but cooperates With the pressure upon they edges of the leather 1 due to the tension of the margin of the pad caused by sinking of the leather into thepad, and that neither of these benefits interferes with the distribution of pressures in the pad by lumps or eXtra thicknesses of the leather Which may be varied by change in the thickness and other characteristics of the tension plates and elastic filling members used and the extent of progressive Vvariation in their thickness:l and character.

' the action about the margin of lt willbe further eviden that because the thicker portions of the leather are driven into the pad to a greater extent than the adjoining port-ions ofthe leather there will be an action by the marginal portions of the pad about them similar, even if of less de ree, to the eather g l pressed.

As many changes could be made in the above process and many apparently widely different embodiments of my invention, within the scope of the claims, constructed without departing from the spirit or scope thereof, it is intended that all matter contained in the accompanying specification and drawings shall be interpreted as illustrative and not in a limiting sense.

Vilhat l claim as my invention is l. lin the manufacture of vegetable tanned sole leather, the steps in the compaction between a die of a press and a cushioning pad in the press of pieces of uneven thickness to substantial uniform firmness, which consists in applying pressure greater than one thousand pounds per square inch, simultaneously to a substantial area of the piece, cushioning the pressure on the flesh side of the leather flexibly in all vertical planes and using cushioning tension at the edge to harden the edges of the leather.

2. The method of simultaneously compacting and finishing substantial areas of vegetable tanned sole leather of unequal thickness, which consists in simultaneously applying compacting pressure of the order of one thousand pounds per square inch or greater to one side of substantially the entire area of a piece of leather while supporting it resiliently and flexibly in all planes perpendicular to the leather to a depth of flexible and resilient support much greater than the diderence in thicknesses of leather in the area compressed, whereby abruptness of variation is avoided.

3. The method of simultaneously compacting and finishing substantial areas of vegetable tanned sole leather or the like of unequal thicknesses, which consists in applying compact-ing pressure of the order of one thousand pounds per square inch or greater to one side of the leather, concurrently pressing it resiliently to different extents, varying directly with he thicknesses, on trie other side and distributing the difference in pressure for different thicknesses of leather compressed. progressively by reason of the resilience of the pressure, whereby the area oli-resilient compre; ion is increased and the extent of compression is reduced as the distance from the thicker parts of the leather increases.

4l. The method of simultaneously compacting and finishing substantial areas of vegetable tanned sole leather c-r the like of unequal thicknesses, which consists in applying compacting pressure 4of the order of one thousand pounds per square inch and upward, si-

multaneously 'over a substantial area of the leather between a firm surface and a resilient surface locally yielding in all vertical planes and thus embedding the leather beneath the resilient surface and hence setting up tension in the margin of the resilient surface and tightening the margin against the leather to intensify the pressure at the edge of the leath` er as compared with the pressure otherwise available there, the pressure conforming to the surface at all points.

5. The method of adjusting the pressure upon a piece of leather being compressed at compacting pressures which consists in shifting the plane of one of the compacting surfaces of the press to partly equalize pressure across the surface while maintaining the lateral position of the compacting surface practically unchanged and in concurrently exerting locally yielding resilient pressure in all planes perpendicular to the leather over a substantial area of the surface of the leather.

G. In the pressing art using a resilient pad made up of highly compressible resilient material between substantially non-compressible flexible sheets, the method which consists in causing a relatively quick initial sagging of the leather into the pad with a rapid stop to the sag by means of perforations in the compressible resilient material at intervals, to provide for local flow of the material initially into the openings provided.

7. rThe process of transmitting pressure for the purpose of hardening leather which consists in maintaining one side of the leather in a plane, in applying to the other side compacting pressure resiliently and flexibly in all planes vertical to the leather concurrently over a substantial surface of the leather and in distributing the differences in pressure for different leather thicknesses progressively in the backing by which the pressure is applied so that the area of deformation increases and the lateral extent of deformation decreases within the packing as the distance beneath the surface of the packing increases.

8. The method of compacting and finishing substantial areas of vegetable tanned sole leather of unequal thicknesses which consists in maintaining one side of the leather plane, in heating that side of the leather and in concurrently pressing the opposite side of the leather resiliently and flexibly within all planes perpendicular to the surface of the leather throughout a substantial area of said surface;

9. The method of compacting vegetable tanned sole leather or the like which consists in maintaining the grain side of the leather rigidly in a plane and in resiliently applying pressure conforming to the surface at all points upon the esh side of the leather concurrently throughout the entire surface of the leather.

10. The method of compacting vegetable tanned sole leather or the like which consists in maintaining the grain side of the leather rigidly in a plane and in resiliently applying pressure of the order of one thousand pounds per square inch or greater concurrently, conforming to the surface at all points throughout the flesh side thereof and varying locally in pressure With the resistance of the leather to compression, progressively greater pressure being applied to thick and lirmer parts of the leather than to thin and softer parts of the leather.

11. rlhe method of compacting vegetable tanned sole leather or the like which consists in maintaining the grain side of the leather rigidly in a plane and in resiliently applying pressure conforming to the surface at all points, of the order of one thousand pounds per square inch or greater, concurrently upon every point of the flesh side thereof, Which pressure is increased at the edges.

12. The method of compactlng vegetable tanned sole leather or the like Which consists in maintaining the grain side of the leather rigidly in a plane and in resiliently applying pressure conforming to the surface at all points and of the order of one thousand pounds per square inch or greater to the flesh side of the leather, the moment of pressure upon any unit area of the leather on one side of the press being made equal to the inoment of the pressure upon any other unit area and the plane of one of the compacting surfaces being adapted to shift to equalize these pressures.

13. The method of compacting vegetable ,tanned sole leather or the like Which consists in maintaining the grain side of the leather rigidly in a plane and in applying pressure resiliently and of the order of one thousand pounds per square inch or over, concurrently to a considerable area of the flesh side of the leather and of increasingly greater pressures locally to thicker portions of the leather, the pressure conforming to the surface at all points.

14. The method of compacting vegetable tanned sole leather or the like Which consists in maintaining the grain side of the leather rigidly in a plane and in applying pressure resiliently of the order of one thousand pounds or greater per square inch, concurrently over a large area on the flesh side While allowing the grain side of the leather to creep in its rigid plane, the pressure conforming to the surface at all points.

In Witness whereof I have hereunto set my hand.

CHARLES GE ORGE SHAW.

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