US3302255A

US3302255A - Foundry mold pattern arrangement

Info

Publication number: US3302255A
Application number: US331605A
Authority: US
Inventors: Jr John A Wagner
Original assignee: Wagner Castings Co
Current assignee: Wagner Castings Co
Priority date: 1963-12-18
Filing date: 1963-12-18
Publication date: 1967-02-07
Anticipated expiration: 1984-02-07

Description

Feb. 7, 1967 J. A.'WAGNER, JR 3,

FOUNDRY MOLD PATTERN ARRANGEMENT 2 Sheets-Sheet 1 Filed Dec. 18, 1965 m at ENTOR J0 Armin/5f W wt 1967 J. A. WAGNER, JR 3,302,255

FOUNDRY MOLD PATTERN ARRANGEMENT 2 Sheets$heet 8 Filed D80. 18, 1963 United States Patent 3,302,255 FOUNDRY MOLD PATTERN ARRANGEMENT John A. Wagner, J12, Decatur, 11]., assignor to Wagner Castings Company, Decatur, 111., a corporation of Delaware Filed Dec. 18, 1963, Ser. No. 331,605 6 Claims. (Cl. 22-157) This invention relates to pattern arrangements for making foundry sand molds and, more particularly, to

such arrangements in which the pattern is on a removable insert member retained and precisely positioned within a pattern frame or stool during mold-making and to arrangements for precisely positioning the pattern insert within the stool or frame for accurate registering of cope and drag mold parts.

As will be understood, foundry sand molds for metal castings may be made, particularly on automatic moldmaking machinery, by forming a pattern in the shape of the casting to be made, surrounding the pattern with a mold flask or box, and blowing or otherwise introducing molding sand into the flask on top of the pattern to form a sand mold with cavities therein conforming to the pattern. When the shape of the casting to be made is such that the mold will be in two separate parts which are put together face to facei.e., cope and drag molds a separate pattern is needed for each of the mold parts, and the cavities formed by the pattern in each mold part must be properly oriented with respect to each other so that, when the two mold parts are put together, the cavities in each register with each other to form the desired shape of casting and, preferably, with a minimum parting line visible on the casting where the two mold parts fitted together during the pouring of metal.

Although, conventionally, the patterns for making such cope and drag molds may be integrally a part of a large plate on which the mold flask rests, it may be desired for the patterns to be mounted on or integral with a flat insert arrangement inserted in a frame or stool affixed to the mold-making machinery and which receives the molding box or flask around the pattern. In this way, each individual pattern does not have to include the entire flask-receiving surface, and it is even possible to include a variety of different and separate small patterns within the same frame or stool, while simplifying somewhat the handling and storage and changing of patterns. In any event, it is generally to insert types of pattern arrangements and the pattern frames or stools therefor that this invention relates. As will be understood, the pattern inserts themselves may be made of a variety of materials, such as metal, plastic, wood, etc., or the patterns of such materials may be mounted on a flat insert plate, all in conventional or well understood manner.

With cope and drag molds, as will be understood and particularly where parts of several different castings are to be cast in the same mold, it is extremely important for satisfactory results that the patterns for the separate cope and drag parts of the mold be precisely oriented on the inserts for as nearly perfect .as possible register when the .two halves of the mold are placed together to form the complete mold. conventionally, the cope and drag mold parts are aligned with each other by aligning pins in the respective flasks. Hence, precise registration of the cope and drag mold cavities requires precise orienting of the pattern portions horizontally within the respective flasks. With insert type pattern arrangements, a part of such registering orientation is achieved during the actual manufacture of the cope and drag insert patterns, and considerable thought, development, and attention has gone into this problem of how 3,302,255 Patented Feb. 7, 1967 to produce mold pattern inserts for separate cope and drag mold parts on which the pattern surfaces will precisely register one with the other when the mold parts are made and placed together-see, for example, Patent No. 3,004,311.

If a pattern insert technique is utilized, as opposed to the situation where the pattern is actually formed on or integral with the supporting stool which will receive the flask and in which flask locating pins are positioned at the time of making the pattern, the greatest precision in producing identically registering cope and drag pattern inserts will not produce precisely registered finished mold cavities except as the respective cope and drag inserts are positioned with equal precision within their respective pattern insert frames or stools. In a highly automated and mass production foundry, however, it may be desired to achieve such precise positioning of cope and drag inserts within their respective stools with a minimum of close tolerance machining and in a manner which permits rapidly changing from one pattern insert to another as the demands of production indicate.

If it is attempted to rely merely on the outside dimensions of the pattern insert itself as positioning or locating criteria for precisely positioning the pattern insert within the stool or frame therefore, precise and close tolerance machining of all four edges of the insert may be required, even if a plastic or other cushioning layer is interposed between the edges of the pattern insert and the stool or frame to receive it. Furthermore, if it is the edges all around the pattern insert which define the positioning thereof in the frame, the insert rnust fit the frame opening to tolerances of within a few thousandths of an inch in order to achieve similarly close tolerance registration between cope and drag pattern parts, but such a tight fit complicates considerably the problem of changing from one insert to another, and may readily be disrupted, particularly in automatic sand blowing molding apparatus, by the tremendous erosion experienced as a result of constantly blowing molding sand against the face of the pattern and insert frame or stool therefor. If, on the other hand, such tolerance loss from normal erosion is attempted to be prevented by utilization of erosion-resistant materials for either the frame or the edges of the pattern, the pattern-making operation and resulting mold-making operation may become commercially impractical from a cost standpoint.

In considering the foregoing, it is important to realize, as well understood, that a production run of 10,000 identical castings (which is not a very large run in, for example, the automotive field) may require the making of 10,000 separate sand moldsi.e., 10,000 cope parts and 10,000 drag parts. With highly automated mold-making machinery operating continuous, the erosion of pattern and pattern plates and pat-tern stools merely from having molding sand blow forcibly thereagainst to form the molds is very substantial and contributes one of the greater problems in connection with obtaining and maintaining close tolerance precision or identicalness as between the positioning of cope and drag pattern parts within cope and drag mold flasks so that the desired ultimate registry of the cavities in the cope and drag mold parts will be achieved merely from locating pins in the flasks themselves outside the mold proper.

According to this invention, however, arrangements and techniques are provided for achieving close tolerance and highly precise horizontal orientation or registry of pattern inserts in insert frames or stools thereforwith a minimum of precise machining of the pattern inserts themselves and under circumstances where the normally encountered tolerance-losing effects of erosion from sand blowing are minimized or readily accommodated, as well as providing for rapid changing of pattern inserts because of utilizing a pattern insert which need not tightly and precisely fit the cavity in the insert frame or stool with the same close tolerance as is to be expected of the horizontal positioning of the pattern with respect to the mold flask supported by the stool. One manner of achieving the foregoing utilizes erosion-resistant dowels positioned on a horizontal centerline of the pattern and frame or stool therefor and in semi-cylindrical recesses in both the pattern and stool as locating parameters with respect to which the pattern parts are readily oriented on both cope and drag inserts for ultimate registration of cope and drag mold parts, and so that virtually the only close tolerance machining or precision fitting or mutual indexing of cope and drag pattern inserts occurs only in the machining and orientation of such semi-cylindrical recesses at each end of each pattern insert, rather than all along the entire edge surfaces thereof; and, as a further feature of this invention, the foregoing permits a much looser fit of an insert into an insert frame or stool, merely because the four sides of the insert do not have to fit snugly into the pocket of the stool, for enhancing the ease of change from one pattern insert to another, whether or not there may be also provided around the insert a plastic or resilient cushion for erosion prevention or otherwise.

With the foregoing and additional objects in view, this invention will now be described in more detail, and other objects and advantages thereof will be apparent from the following description, the accompanying drawings, and the appended claims.

In the drawings:

FIG. 1 is an exploded view in elevation of a pattern insert and stool. arrangement for cope and drag molds embodying and for practicing this invention;

FIG. 2 is a top plan view of the apparatus of FIG. 1 in assembled condition; and

FIG. 3 is a vertical section through the apparatus of FIGS. 1 and 2 along the line 33 of FIG. 2.

Referring to the drawings, in which like reference characters designates like parts throughout the several views thereof, there is shown a pattern insert frame or stool and a removable pattern insert 11, carrying on the upper surface thereof pattern portions 12. Conventional molding flask locating pins 13 and 14 (the former being round and the latter non-round in conventional manner to assure proper end-for-cnd orientation of the cope and drag mold parts) are also provided, as well as insert-locating dowels 15 and 16 described in more detail hereafter. As will be understood, and with particular reference to the assembled arrangement of FIG. 3, a conventional mold flask is positioned on the upper surface of pattern stool 10 and located thereon by pins 13 and 14, after which molding sand is blown or otherwise introduced into the interior of the flask to form a sand mold on the face of pattern insert 11 and having mold cavities formed around pattern portions 12 thereon. The pattern portions 12 may be integral with pattern insert 11 (and formed of a variety of materials such as metal, wood, plastic, etc.) or may be separately applied or aflixed to the face of a flat plate 11 as well understood in this art.

Semi-cylindrical recesses 20 and 21, with bearing surfaces 33 and 34, respectively, are provided at opposite ends of the insert-receiving cavity 19 in frame 10 and precisely aligned on the centerline thereof. Corresponding

recesses

22 and 23, with

bearing surfaces

30 and 31, respectively, are provided in opposite ends of pattern insert 11 and similarly precisely aligned with the centerline thereof. In this manner, locating dowels 15 and 16 are accommodated, one in each of the

cooperating recesses

20, 22 and 21, 23 and against the

bearing surfaces

30, 34 and 31, 33 therein so as to determine the precise lateral or horizontal positioning of insert 11 in recess 19 of pattern insert stool 10, it being understood that the remaining portions of the vertical edges 24, 26 and 28 of insert 11 need not be precisely fitting with the edges of cavity 19 in frame 10. It may also be desired to provide a resilient cushion 25 of plastic or other material around the inside of cavity 19 of frame 10 merely for the purpose of sealing against the edges 24, 26 and 28 of insert 11 to prevent or minimize entry of molding sand between the insert and the frame, but the entire positioning or orientation of pattern insert 11 with respect to frame 10 (and, particularly, flask locating pins 13 and 14 thereof) is still provided primarily by dowels 15 and 16.

As will be apparent from the drawings, it is preferred that dowels 15 and 16 have different diameters, merely to aid in end-for-end identification, and satisfactory results in accordance herewith have been achieved by providing dowel 15 with a diameter of 1.25 inches and dowel 16 with a diameter of 1.50 inches. In this manner, only the bearing surfaces 30'and 31 of the

semi-cylindrical cavities

22 and 23 in pattern insert 11 need be precisely machined to within the close tolerance precision requirements for positioning the insert, while the remainder of the edges 24, 26 and 28 of the insert 11 need not be machined at all since as-cast dimensions are appropriate, particularly when fitting clearance between pattern insert 11 and insert frame 10 are filled with resilient cushion 25. Similarly, the only portion of the insert frame itself which must be precisely machined are the bearing surfaces 33 and 34 of the semi-cylindrical recesses 20 and 21, so that the remainder of the apparatus need not be precisely made, nor are losses of tolerances therein critical, which losses may occur from erosion by the blown sand. Even if some tolerance loss or erosion occurs in time adjacent the locating dowels 15 and 16, this is readily corrected in a manner which permits continued use of the equipment and continued precise positioning of the various inserts 11, even if such erosion might require replacing the dowels with slightly larger sizes, etc. In any event, the entire positioning for registry of cope and drag pattern 11 in their respective stools 10 is achieved to precisions of within a few thousandths of an inch merely by the machining and locating of the

bearing surfaces

30, 34 and 31, 33 of the

cooperating recesses

20, 22 and 21, 23 on the centerline of the inserts and stools.

As a further advantage of the locating procedure described herein as it pertains to the time consumed in making the inserts, the cost involved and the ease with which they are made, it has been found that the relatively small amount of precision machining involved here is even further reduced by having the

bearing surfaces

30, 31 of the

recesses

22, 23 in the inserts of both the cope portion and the drag portion of a particular pattern machined in one operation. That is, the inserts of both the cope and drag portionsof the pattern are placed together, and the machining of the recesses at each end thereof are done at the same time. This not only reduces the cost of the necessary machining, but also provides for an even more accurate alignment of the mold halves made from each portion because the inserts of each will have exactly the same bearing surfaces against the locating dowels which are placed against them.

In addition, as an adjunct to the simplified insert locating technique described herein, it has been found that this technique is particularly advantageous to the pattern maker. One of the prime difficulties in the procedure of making a pattern is locating the actual pattern accurately on the insert. It has been found here that the pattern maker, by using the centerline between the recesses at each end of the insert as a guide, can center the pattern thereon with much more ease and can precisely center the cope and drag portion of the pattern on their individual inserts for precise registration of the molds formed thereby when the latter are placed together.

Therefore, there are provided by this invention arrangements for precision orientation of pattern inserts in insert frames or stools whereby a bare minimum of precision machining is necessary to bring about simple, accurate locating of the inserts. Furthermore, the insertion and removal of the inserts from the stool is made considerably easier during the routine changing operation thereof from one pattern to another merely because the vertical surfaces of the sides of the insert do not have to precisely fit the vertical sides of the pocket into which the insert is placed.

The techniques disclosed here have produced satisfactory results for working patterns which can be cast integrally with the insert, mounted on flat inserts, or cast in segments and mounted in pockets formed in the inserts with the only requirement being that the patterns be located on the inserts in the proper relationship to the recesses which are machined therein.

While the apparatus and techniques herein described form preferred embodiments of this invention, this invention is not limited to those precise apparatus and techniques, and changes may be made therein without departing from the scope of this invention which is defined in the appended claims.

What is claimed is:

1. In a pattern stool of the character described for use in retaining a pattern during the formation of cope and drag portions of a foundry sand mold in a mold flash positioned on said stool and surrounding said pattern and for maintaining precise registration and positioning of said pattern with respect to said flask for precise matching of said cope and drag mold portions to form a complete foundry mold, the combination which comprises a substantially flat surface on said stool for receiving and supporting a flask for one of said mold portions, means for precisely and repeatedly positioning a flask on said stool in a predetermined orientation thereon matching and registering with a mold portion disposed thereon, a recess in a stool for receiving said pattern insert therein and disposed on said stool within the area of said flat surface thereof enclosed by said flask, and locating means positioned at each opposite side in said recess for engaging cooperating locating means on a pattern insert when positioned in said recess for precise registration and positioning of said insert and said pattern thereon with respect to said stool and said flask thereon, said recess being larger than said pattern insert as inserted therein and said cooperating locating means in said recess and on said pattern insert being substantially spaced apart for location and registration of spaced points as substantially the sole locating means for positioning said pattern insert in said recess.

2. In a pattern stool of the character described for use in retaining a pattern during the formation of cope and drag portions of a foundry sand mold in a mold flask positioned on said stool and surrounding said pattern and for maintaining precise registration and positioning of a pattern insert with said pattern thereon with respect to said flask for precise matching of said cope and drag mold portions to form a complete foundry mold, the combination which comprises a substantially flat surface on said stool for receiving and supporting a flask for one of said mold portions, means for precisely and repeatedly positioning said flask on said stool in a predetermined orientation thereon matching and registering with the orientation of a flask placed thereon for the other said mold portion, a recessin said stool for receiving a pattern insert therein and disposed on said stool within the area of said flat surface thereof enclosed by said flask, and locating means including locating dowels and cooperating locating surfaces in said recess, and on said pattern insert disposed therein for precise registration and positioning of said insert with respect to said stool and said means thereon for positioning said flask.

3. In a pattern stool of the character described for use in retaining a pattern during the formation of cope and drag portions of a foundry sand mold in a mold flask positioned on said stool and surrounding said pattern and for maintaining precise registration and positioning of said pattern with respect to said flask for precise matching of said cope and drag portions to form a complete foundry mold, the combination which comprises a substantially flat surface on said stool for receiving and supporting a flask for one of said mold portions, means for precisely and repeatedly positioning a flask on said stool in a predetermined orientation thereon matching and registering with that of a mold portion disposed thereon, a recess in said stool for receiving a pattern insert therein with said pattern disposed thereon and disposed on said stool within the area of said flat surface thereof enclosed by said flask, and locating dowel means in said recess and at opposite ends thereof for engaging locating surfaces on said pattern insert when positioned in said recess for precise registration and positioning of said insert with respect to said stool and said means thereon for positioning said flask.

4. In an arrangement for making foundry molds having separate cope and drag parts each formed separately in mold flasks around a pattern, the combination which comprises a pattern stool 'having a substantially flat upper surface for supporting a flask thereon for said mold parts, means on said stool for precisely positioning and orienting a flask thereon for subsequent precise registration with another flask having the other of said mold parts, a recess in said upper surface of said stool for receiving a pattern insert therein and positioned within the area of said stool surface surrounded by said flask when positioned on said stool, a pattern insert for insertion into said recess and carrying on the upper surface thereof a pattern for one of said cope and drag mold parts, the outer dimensions of said pattern insert being slightly less than said recess in said pattern stool for ready insertion and removal of said insert, cooperating locating and positioning means positioned at each opposite side on said insert and in said recess for engaging and locating said insert in said recess for precise positioning and orientation of said insert with respect to said flask and said locating and orienting means therefor whereby precise positioning and orienting of said patterns for each of said cope and drag mold parts is effected and maintained with respect to their respective said flasks providing accurate registration of said cope and drag mold parts when the respective flasks containing them are placed together to form a complete foundry mold.

5. In an arrangement for making foundry molds .having separate cope and drag parts each formed separately in mold flasks around a pattern, the combination which comprises a pattern stool having a substantially flat upper surface for supporting individually various flasks placed thereon for said mold parts, means on said stool for precisely positioning and orienting said flasks thereon for subsequent precise registration with another flask having the interfitting half of one of said mold parts, a recess in said upper surface of said stool for receiving a pattern therein and positioned within the area of said stool surface surrounded by one of said flasks when positioned on said stool, a pattern insert for insertion into said recess and carrying on the upper surface thereof a pattern for one of said cope and drag mold parts, the outer dimensions of said pattern insert being slightly less than said recess in said pattern stool for ready insertion and removal of said insert, locating and positioning dowel means in said recess, cooperating locating surfaces on said insert for engaging said dowel means for precise positioning and orientation of said insert within said recess and with respect to said flask and said locating and orienting means therefor whereby precise positioning and orienting of said patterns for each of said cope and drag mold parts is effected and maintained with respect to said flask providing accurate registration of said cope and drag mold parts when the respective flasks containing them are placed together to form a complete foundry mold.

6. In an arrangement for making foundry molds having separate cope and drag parts each formed separately in mold flasks around a pattern, the combination which 7 comprises a pattern stool having a substantially flat upper surface for supporting a flask thereon for one of said mold parts, means on said stool for precisely positioning and orienting a flask thereon for subsequent precise registration with another flask having the other of said mold parts, a recess in said upper surface of said stool for receiving a pattern therein and positioned Within the area of said stool surface surrounded by said flask when positioned on said stool, a pattern insert for insertion into said recess and carrying on the upper surface thereof a pattern for one of said cope and drag mold parts, the outer dimensions of said pattern insert being slightly less than said recess in said pattern stool for ready insertion and removal of said insert, locating and positioning dowel means at opposite ends of said recess, precisely machined locating surfaces on said insert for engaging said locating dowel means for precise positioning and orientation of said insert within said recess and with respect to said References Cited by the Examiner UNITED STATES PATENTS 1,570,989 1/1926 Bossert 22157 2,070,945 2/1927 Jones 22157 3,121,267 2/1964 Snoeyenbos et al. 22157 I. SPENCER OVERHOLSER, Primary Examiner.

MARCUS U. LYONS, Examiner.

E. MAR, Assistant Examiner.

Claims

2. IN A PATTERN STOOL OF THE CHARACTER DESCRIBED FOR USE IN RETAINING A PATTERN DURING THE FORMATION OF COPE AND DRAG PORTIONS OF A FOUNDRY SAND MOLD IN A MOLD FLASK POSITIONED ON SAID STOOL AND SURROUNDING SAID PATTERN AND FOR MAINTAINING PRECISE REGISTRATION AND POSITIONING OF A PATTERN INSERT WITH SAID PATTERN THEREON WITH RESPECT TO SAID FLASK FOR PRECISE MATCHING OF SAID COPE AND DRAG MOLD PORTIONS TO FORM A COMPLETE FOUNDRY MOLD, THE COMBINATION WHICH COMPRISES A SUBSTANTIALLY FLAT SURFACE ON SAID STOOL FOR RECEIVING AND SUPPORTING A FLASK FOR ONE OF SAID MOLD PORTIONS, MEANS FOR PRECISELY AND REPEATEDLY POSITIONING SAID FLASK ON SAID STOOL IN A PREDETERMINED ORIENTATION THEREON MATCHING AND REGISTERING WITH THE ORIENTATION OF A FLASK PLACED THEREON FOR THE OTHER SAID MOLD PORTION, A RECESS IN SAID STOOL FOR RECEIVING A PATTERN INSERT THEREIN AND DISPOSED ON SAID STOOL WITHIN THE AREA OF SAID FLAT SURFACE THEREOF ENCLOSED BY SAID FLASK, AND LOCATING MEANS INCLUDING LOCATING DOWELS AND COOPERATING LOCATING SURFACES IN SAID RECESS, AND ON SAID PATTERN INSERT DISPOSED THEREIN FOR PRECISE REGISTRATION AND POSITIONING OF SAID INSERT WITH RESPECT TO SAID STOOL AND SAID MEANS THEREON FOR POSITIONING SAID FLASK.