US2681484A - Pattern positioning device - Google Patents

Description

June 22, 1954 1 A, STROMMEN 2,681,484 A PATTERN POSITIONING DEVICE Filed Jan. 14, 1952 2 sheets-sheet 1 June 22, 1954 J. A. sTRoMMEN 2,681,484

' PATTERN PosIToNING DEyIE Filed Jn. 14, 1952 2 sheets-sheet 2 D MW m :12f-

,axwmw Patented June 22, 1954 STATES FiiiiffENT OFFICE PATTERN Psfiimo DEVICE John .A. Strommen, Milwaukee, 'Wis., assigner to Allis-Chalmers -Manufacturing Company, .Mil-

.ApplicationiJanuaryl14, 1952, Serial No. 266,396

I Claims. l vThis invention relates Ato molding apparatus and ismore particularly conoernedWith-.the provision of apparatus for eiectively'utilizing a pattern segment in the formation of molds.

AIn oneof its aspectso the present invention is of .particular advantage, although :not Vin `any manner limited, in the production of annular molds. `Annular `molds vhave heretofore been made `by usinga segmental pattern and rotating it aroundits center -insteps,fsand being lpacked against the circumferential outer surface of the pattern at -eachsten This type of pattern has previously been made iup of at least twoseparate parts, .so assembled that manual removal of onel part, which .is usually in the nature of a wedge, vis necessary before the other partcan be withdrawn. from the mold. i Insertion. of the wedge functions to correctly position the other part of the pattern in a .predetermined relation to a surrounding mold .ask or other `suitable structure.

`'Ihecost involved in using Vpatterns comprising complementary parts, at leastone of rwhich is a wedge, is excessive because al completely new pattern comprising thetwo-parts is required foreach mold having a .materially different diameter.

Moreover, Wedge parts which are usually Adri-ven into place, soon beccmewdamaged or Worn sufficiently to requireffrequent replacement. In .addition, a high degree of `sltill and considerable effort .are `required rin effectively .utilizing .such patterns andconsequently. thelabor costis high.

`The presentinvention has as anobject to prov'ide yapparatus "for effectively .utilizing` a pattern segment in an improved-manner minimizing the time, eiort and skill necessary Vfor thefproduction of satisfactory molds.

Another object of this invention is the` provision of 'apparatus for eiectively positioning and manipulating pattern segments `of different sizes Wheibykthe cost ofproviding patterns for molds of different `dimensions is greatly reduced, in that Aonlyxthe unitary pattern segment'need be changed;

'Stillanother ob'je'ct of the presentinvention is "the provision of apparatus "of theforegoing type whichaffords the advantage ofbeing foolproofin operation, which .is `simple and inexpensiveto 'constructand maintain, andwhichaffords readyadjustment of the" position of 'a pattern segment associated therewith.

' Other objects andadvantages will appear from the `following 'descriptiontofa structure'illustratng an embodiment of .the invention, reference being hadto .the accompanying drawings, in which:

Aiiigl isa-'topwewp'f an apparatus embodying i2 the invention with a pattern segment disposed :in its mold forming position;

Fig. `2 isa top View lsimilar `to Fig. `l 'showing thepattern segment 4in its .innermost position relative to the mold;

Fig. 3 lis a top view `similar to Fig. :2 showing the position of the pattern segment after counterclockwise rotation of the same through anangle of nearly- Fig. 4 is a top view similar to Fig.3 showing the pattern segment .disposed-in its next .mold forming position;

5 is a vertical section taken `along line V-V of Fig. 4;

Fig. 6 is a vertical section taken `along lline VI--VI of Fig. 3;

Fig. 7 is an enlarged topview similar -to Fig. 1 with the flask omitted in the interest of clarity and with thepattern segment shown as an integral part of a hub portion o1" the pattern moving mechanism;

Fig. 8 is anxenlarged top-view similar toEig. 7 with the pattern shown in its innermost `position in conformity with Fig. 2;

Fig. 9 is a vertical section taken along the line XI-XI of Fig. eiwiththe wrench and aportion of the patternsegment omitted in the interest ofclarity; and

Fig. l0 is a schematicdiagram showingessential coacting parts of the pattern positioningapparatus in proper Working position.

As shown in the drawings, an apparatus embodying the invention comprises an arcuate pattern segment -I rigidly secured `to a split hub memberZ, whichis `held together by bolts-3 and nuts 4` which coactwith Bange portions ofsaid split hub. It is usually `preferableto detachably secure segment I tosplithubmember `2` by any suitable means, which is designated generally by the numeral V5. An eccentric collar 6 is journaled forrotationin splithub `2,.and is Yrotatably ldisposed on a verticalfspindle -1 which is rigidlysupported ina .spindle receptacle. Receptacle `Il is xedlysecured `to amoldboard` or other suitable surface 9 forming the bottom .ofv flask I I. Eccentric collar Sais provided with apairwofrecesses. I2 inits outer surface, which areadapted toreceive complementary projections on a-special collar .rotating wrench I 3 `as shownin Figs. .7 and'.

A collar stoppeg I4.is rigidly xed infsplit.' hub 2 so that it iscoactable with theopposite ends or shoulderportions I6 of a `protru'dinglange I1 on collar'li, as best shown in .Figs. V'7 and-:8. Items I4, I'E and I'I maybe consideredasmeans for'limiting rotation of collar 6 relative to hub 2.

.n since the rotational limits of collar 6 relative to split hub 2 are reached when one or the other of ends I5 of flange I'I engages stop peg I4. The eccentric collar is provided with a lip portion i 3, which coacts with split hub 2 and prevents eccentric collar 6 from slipping, in response to gravity, through split hub 2 and out of Contact with it.

In operation, the entire assembly, which comprises the elements I, 2, 6, 7, and associated parts, is centrally disposed in the flask I I, and eccentric collar 6 is rotated to place pattern segment I in its maximum radially outward position as governed by the coaction of flange Il and stop peg Ill. Y

While the assembly aforementioned is in this position, side boards I9 are placed against the edge of pattern l and pushed radially outward against the inner surface of flask cheek 2 l Next, molding material is packed in the space defined by the outer peripheral surface of pattern l, the

inner surface of ilask cheek 2l, and the side boards I9. After this packing operation is completed, side boards I9 are removed, and eccentric collar Ei is preferably rotated to its maximum radially inward position, which in the case of the present invention is 135. This positions the apparatus as shown by Fig. 2.

If desired, a smaller angular rotation is permissible, this being determined by the amount of clearance which must be provided between the pattern and the mold in order to conveniently allow for rotation of the pattern. When using a 90 pattern segment, the collar t should be 45 from the position it would be in if it were to have its thickest or maximum eccentric portion between its center of rotation and the circumferential midpoint of the pattern segment against which molding material is to be packed. This positioning insures that the pattern segment will not be jammed into the packed molding sand as the eccentric collar is rotated to cause withdrawal of the pattern segment. Assume collar 6 initially positioned so that its maximumY eccentric portion is between the center of rotation ofthe collar and the circumferential midpoint of the pattern segment. When the eccentric collar is `rotated from its initial position countercloclf.- wise to cause withdrawal of the pattern segment, the edge of the pattern segment adjacent the radial edge B, as shown in Fig. l0, will move to the left at a faster rate than it will withdraw inwardly and it will be jammed into the packed molding sand damaging the mold. Damage to the mold can be obviated by designing the pattern segment so that the circumference of the pattern segment is concentric to the periphery of flask II when the thickest portion of collar 6 is at least 45 from the position it would be in if its thickest portion were between its center of rotation and the circumferential midpoint of the pattern segment. This allows the edge of the pattern segment adjacent to the radial edge B to move inward at a faster rate than to the left when the eccentric collar is rotated to cause withdrawal. As a result, the pattern segment is cleanly withdrawn from the mold surface without damaging it. In Fig. 10, the circumference of pattern segment I is concentric to center pointF and therefore concentric to the periphery of any flask having a center of arc at point F, although the thickest portion of collar 6 is located at point A. Generally, if a pattern segment covering more or less than 90 is to be used, the ecentric collar 6 can be allowed to approach no closer to its full radially outward CAD position than half the number of degrees covered by the pattern segment.

Next the pattern and its associated assembly is rotated in iiask II around spindle 7. The extent of this rotation is preferably slightly less than the number of degrees covered by the pattern segment so as to effect an overlapping of the pattern with the previously packed molding material as shown in Figs. 3 and 6. When this has been done, eccentric collar E is rotated to a maximum radially outward position governed by the coaction of flange I'I and stop peg I4. One side board i9 is placed against the open edge of pattern I and pushed radially outward against the inner surface of ask cheek 2|, after which sand is packed in the space between pattern I, flask cheek 2i, side board I9, and that part of the mold previously formed in the rst operation. This results in an arrangement of the apparatus such as shown in Figs. 4 and 5.

The steps just described are repeated until pattern segment I has made a complete revolution around spindle 'I and a circular mold has been formed in iiask II. This completes the formation of a circular mold such as is indicated in the drawings, whereafter the flask and mold forming apparatus arerremoved as desired.

In Fig. 10, the pattern segment I is shown in its ramming position with the point of maximum eccentricity A on collar 6 disposed in radial alignment with the true center of rotation F of pattern segment l and a selected radial edge B of the segment. Obviously the point of minimum eccentricity C on collar 6 will always be spaced 180o from the point of maximum eccentricity A. The other radial edge D of pattern segment I is spaced X in a counterclockwise direction from the point of minimum eccentricity C on collar 6. Consequently collar 5 can be rotated 2X in a counterclockwise direction from the position shown in Fig. 10 without effecting any change in the angular position of segment l. That this is so is obvious, when it is considered that during rotation through an angle of XQ in this direction from the position shown, radial edge D will move inward until point C is in radial alignment with segment edge D, and that during the next X of rotation in the same direction, radial edge D will move outward until a point G on collar 6, which is equally as eccentric as the point E thereon, is disposed in radial alignment with segment edge D. A further rotation of eccentric collar 5 in the same direction is impractical for making molds as it will obviously force that portion of the outer face of the segment adjacent radial edge D outward beyond its initial position.

The foregoing `demonstrates Ithat in the formation of annular molds the maximum permissible angle of rotation of eccentric collar B relative to pattern segment 1, when the latter is in its proper mold ramming position, is always 2X, iQe., .twice the angle enclosed between the radial lines FE and FC. The arcuate pattern segment I, when expressed in terms ofthe langle included between lines FE and FC is always equal to 180-X. Now, if MR@ designates the maximum angle of rotationof collar 6 relative to pattern segment I, MR=2X and, if S designates the angle of the arcuate pattern segment I, then S=180-X, which may be written X=180-S. Since MR=2X it is further apparent that which is the same as MRc=36-2S. Y

Thus the maximum practical rotation of patternisegment I :can never; exceed the includedlangie-fof Lthesegment because a `:rotation of` segment Ithroughra greater angle -thanthat `aforemenmentioned willlleave a, `gap between the lagging radial edge offsegment `I :and-the adjacent end offthe moldsection :previously formed. Therefore, .nothing is to be gained by .adopting an arrangement aifording a rotation fof segment I in excess ofthe angle which is encompassed by its arcuate* surface. In fact, the laggingedge of segment II :preferably overlaps thefadjacent end of thehpreviously formed `mold section to insure the formation of a mold Vhaving a flawless inner surfasce land to prevent breaking raway of the yadjacent Aledge of the previously formed mold during the succeeding ramming operation. Consequentlygas -a practical matter,` the maximum rotationof pattern segment I (MRS) -should never exceed the angle encompassed by pattern segment I (S). VThe Amaximum pattern segment rotation (MRS) relativetc eccentric collar 5, after the Acollar has been rotated through its maximum angle `of rotation (MRC), `is equal to MZRC or -2X, as previously explained. This fact may -be `confirmed by obserbing that `during rota-tion of--segment I relative to collar t through an angle of "X" in the same direction in which collar 6 was-'rotated radial edge D will move inwardly frompointG on collar 6 until it is in radial alignment with `-the fpoint of minimum eccentricity C thereon, and yduring the Iensuing rotation of Xc in the same direction, radial edge D will move outward -until it fallsin radial alignment with point E on collar 6, which is equally as eccentric as point thereon, and which therefore positions radial edge D in itsinitially radially outward position. A further rotation of pattern segment I relative to eccentric collar 6 is impractical fonmaking molds as it will obviously force Ithat portion of the outer face of segment I, adjacent radial edge D, outward 'beyond its proper mold forming Ipositio-n.

Since MRS-42X, and since Miter-2X as proven earlier, it follows that MRS=MRC- Now, since MRS should never exceed S as previously explained, for all `practical purposes MRS=S- This being so, 'formula MR=360e2S may be written S=`360f-2S, or 3S=360- Solvingi'this formula,` S. MRS, and "MR-c all equal 12o".

A pattern segment of 120 is the largest which canbe advancedfrom its initial ramming vposition to its next renaming` position so that the full arcuate extent or" the segment is presented in continuous mold forming relation to the previously rammed 4mold section, in only two steps. This two stepV process is accomplished by first rotating eccentric collar lF(120") relative to pattern segment I andthen rotating segment I(120) relative to collar t. Obviously a smaller pattern segment may be effectively used in a similar manner. In addition alargcr segment may be eiiectively moved `from one practical ramming position to the'next in either `oi two ways: (1) `rotation of eccentric collar 5 relative to pattern Asegment i through an -angle somewhat less than MRC, followed "by simultaneous rotation of eccentric collar 6 and pattern segment I as a uni-t, relative to the contemplated mold until the full arcuate extent of segment I is spaced inwardly from its ramming position, in turn followed by rotation of eccentric collar .Brelative to pattern segment I in an opposite direction until the segment is moved radially outward into its ramming 'position; and `(2) rotation `of eccentric collar 6 through an angletsomewhat ,less ythan MRc .relato 'complete a meldt-with aminimum numiberf` separate ramming operations,` and yet the segment Ishouldbe small enough to be readilywithdrawable from the inner surface `of a mold Vsec*- tion adistance such thatthesegment `can be easilyand quiekly-rotatedimin one rammingiposition to another withoutfcausing `damage to the previously formed mold section. `The positioning apparatus-of the 'present invention is designed `for use with patternsegments of somewhat lessfthan` 1'80",` and therefore, `itiollows that a minimumto three separate ramming operations must vbe executed before a complete annular mold canfbe formed therewith.

Although a pattern segment `of y'is theoretically workable, actually, to obtain va `practicalfdegree of overlap, as previously pointed out, a pattern ysegment `of v120" requires four ramming'f'operations. The factthatthe human 'factor is involved, makes it desirable touse a segmentiless than 120 toavoid a simultaneousor step-by-'step pattern shifting procedure previously described as being possible. Furthermore, thesm'allersegments are less costly to-build andf'rnorelconvenient to use. Experience in forming circular 'moldspf '7 to 8 feet in `diameter has showna 90`-pattern segment to be of satisfactoryV utility yeven though sucha segment requiresve `separaterarrnning operations (allowing for overlap 'for `eachrarnming operation) in order 'to complete an annular mold.

From the Aforegoingit should be obviousto one skilled in the vart that the present invention 'affords a simple, economical and trouble `freeapparatusforforming molds with a unitary pattern segment and that it may be successfully practiced with apparatus differing somewhat fromthe "practical construction. herein shown 'and described for purposes of illustration. Accordingly'it is to be understood that the invention is notinten'ded to belimited to the exact details of construction, combination, and/or operation herein set forth, as various modifications `thereof, within the scope of the appended claims, may occur to` persons skilled in the art.

`It is claimed and desired to secured by Letters Patent:

1. An apparatus for forming a mold having an inner `arcuate face equidistant from the center of arc thereof, said apparatus comp-rising: a spindle 'i'ixedly positionable at said center; an eccentric collar .mounted on said spindle for rotation therearoun'd, said collar having amaximum eccentric portion; `and a pattern segment 'presentingan arcuate surface ior forming saidface. said segment being mounted on said eccentric collar for rotation therearound and being movable in a general radial outward direction. into a mold-forming position in response to a rotation of said collar in a direction effective to move 'said maximum eccentric portion throughfan arc from a `point 4lying outside a central angle :subtended by said arcuate surface to a point lying on-aradial line extending from saidcenterto ra terminal point of said arcuate surface, said arc subtending at said center a second angle adjacent t said central angle, and said segment presenting in said mold-forming position said arcuate surface equidistant from said center.

2. An apparatus for forming a mold having an inner arcuate face equidistant from the center of arc thereof, said apparatus comprising; a spindle xedly positionable at said center; an eccentric collar mounted on said spindle for rotation therearound, said col'iar having a maximum eccentric portion; a hub member having a pattern segment attached thereto presenting an arcuate surface for forming said face, said segment being mounted on said collar for rotation therearound and being movable in a general radial outward direction to place said arcuate surface in a mold-forming position in response to a rotation of said collar in a direction effective to move said maximum eccentric portion through an arc from a rst point lying outside a central angle subtended by said arcuate surface to a second point lying on a radial line extending from said center to a terminal point of said arcuate surface, said arc subtending at said center a second angle adjacent to said central angle, said segment presenting in said mold-forming position said arcuate surface equidistant from said center; and stop means having relatively engageable parts, one of said parts being mounted on said collar and the other of said parts being mounted on said hub member, said parts `being effective upon being brought into engagement to stop said movement of said maximum eccentric portion beyond said second point to prevent said .maximum eccentric portion from being interposed between said spindle and said arcuate surface in the area of said central angle.

3. An apparatus for forming a mold having an Y inner arcuate face equidistant from the center of arc thereof, said apparatus comprising: a spindle iixedly positionable at said center; an eccentric collar mounted on said spindle for rotation therearound, said collar having a maximum eccentric portion; a hub member having'a pattern segment attached thereto presenting an. arcuate surface for forming said face, said segment being mounted on said collar for rotation.

therearound and being movable in a general radial outward direction to place said surface in a mold-forming position in response to a rotation of said collar in a direction effective to move said maximum` eccentric portion through an arc from a point lying outside a central angle subtendel by said arcuate surface to a point lying on a radial lineA extending from said center to a terminal point of said arcuate surface, said arc subtending at said center a second angle adjacent to saidzcentral angle; and stop means having relatively engageable parts, one of said parts being mounted on said collar and the other of said parts being mounted on said hub member, said parts being cooperatively effective to limit relative rotation of said collar with respect to said hub member to prevent said maximum eccentric portion from being interposed between said spindle and said' arcuate surface in the area of said central angle.

4. An apparatus for forming a mold having an inner arcuate face equidistant from the center of arc thereof, said apparatus comprising: a spindle iixedly positionable at said center; an eccentric collar mounted on said spindle for rotation therearound, said collar having a maximum eccentric portion; a hub member having a pattern segment attached thereto presenting an ar- 8 cuate surface for forming said face, said segment being mounted on said collar for rotation therearound andY being movable in a general Vradial outward direction to place said surface in a moldforming position in response to a rotation of said collar in a direction eifective to move said maximum eccentric portion through an are from a rst point lying outside a central angle subtended by said arcuate surface and on a diametral line extending through said center and the center of said arcuate surface to a second point lying on a radial line 'extending from said center to a terminal point of said arcuate surface, said segment being movable in a general radial in- Ward direction to withdraw said surface from said mold-forming position in response to a rotation of said collar in a direction effective to move said maximum eccentric portion through said arc from said second point to said first point, said arc subtending at said center a second angle adjacent to said central angle; and stop means having relatively engageable parts, one of said parts being mounted on said collar and the other of said parts being mounted on said hub member, said parts being eifective upon being brought into engagement in response to said rotation of said collar to limit the maximum relative rotation of said collar with respect to said hub member to prevent said maximum eccentric portion from being interposed between said spindle and said arcuate surface in the area of said central angle. 5. An apparatus for forming a mold having an inner arcuate face equidistant from the center of arc thereof, said apparatus comprising: a spindie iixedly positionable at said center; an eccentric collar mounted on said spindle for rotation therearound, said collar having a maximum eccentric portion; a hub member having a pattern segment attached thereto presenting an arcuate surface for forming said face, said segment being mounted on said collar for rotation therearound and being movable in a general radial direction to place said surface in a mold-forming position in response to a rotation'of said collar in a direction effective to move said maximum eccentric portion through an aro from a point lying outside a central angle subtended by said arcuate surface to a point lying on a radial line extending from said center to a terminal point of said arcuate surface, said arc subtending at Ysaid center a second angle adjacent to said central angle, and said segment presenting 'in said mold-forming position said arcuate surface equidistant from said center; and stop means having relatively engageable parts, one of said parts being mounted on said collar and the other of said parts being mounted on said hub member,

said parts being effective upon being brought into engagement to limit relative rotation of said collar with respect to said hub member to an angle of 360 degrees minus twice said central angle to prevent said maximum eccentric portion from being interposed between said spindle and said surface in the area of said central angle.

References Cited in the le Of this patent UNITED STATES PATENTS

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