US3460607A

US3460607A - Means for providing a choke for in-tube retention of sand in core box or like blow tubes

Info

Publication number: US3460607A
Application number: US496546A
Authority: US
Inventors: Richard L Olson
Original assignee: Dike-O-Seal Inc
Current assignee: Dike-O-Seal Inc
Priority date: 1965-10-15
Filing date: 1965-10-15
Publication date: 1969-08-12
Anticipated expiration: 1986-08-12

Description

MEANS FoR PRovImnG'A CHOKE FOR IN-TUBE RETENTION 0F SAND IN com". BOX OR LIKE BLOW TUBES Filed Oct. 15, 1965 Aux-12,1969 R L. OLSON 3,460,607

Wet

.F .3 57. 0" 1 .:z 7'.4 22' a? Zia an 17 K7 1 Z63 5.9 15 INVENTUR. t @zemL,Q&s0z2

I 3 Y A '7 I ORNE S United States Patent 3,460,607 MEANS FOR PROVIDING A CHOKE FOR IN-TUBE RETENTION OF SAND IN CORE BOX OR LIKE BLOW TUBES Richard L. Olson, Hickory Hills, 111., assignor to Dike-O- Seal, Incorporated, Chicago, Ill., a corporation of Illinois Filed Oct. 15, 1965, Ser. No. 496,546 Int. Cl. B22c 15/24; Bb 1/50 U.S. Cl. 164-200 6 Claims ABSTRACT OF THE DISCLOSURE This invention relates to improvements in means for blowing sand into core boxes or the like, and more particularly concerns a new and improved means for producing a choke for in-tube retention of sand whereby to assure substantially clean breakaway of the core from the delivery opening end of the column of sand in the blow tube.

Heretofore blow tubes or blow passage liners having thereon preformed restrictions or chokes at the delivery end have been widely used in sand mold blowing and more particularly sand core blowing apparatus. This has required the supplying of a virtually infinite number of lengths of blow tubes because the lengths of the blow holes or passages between the inlet and discharge ends necessarily vary greatly due to variations in core contours and thus in the conforming cavities in the mold or box.

An important object of the present invention is to provide a new and improved means for providing sand retaining restrictions or chokes for the purpose described utilizing standardized lengths of blow tubes or blow hole or passage liners.

Another object of the invention is to provide a new and improved means for providing a core box or like blow hole with a sand retaining choke.

A further object of the invention is to provide a new and improved sand restricting choke structure for the blow holes of core boxes and the like.

Other objects, features and advantages of the present invention will be readily apparent from the following detailed description of certain preferred embodiments thereof taken in conjunction with the accompanying drawing, in which:

FIGURE 1 is a fragmentary schematic sectional illustration of a sand core blowing apparatus embodying features of the invention;

FIGURE 2 is a fragmental longitudinal sectional view through a blow tube of the kind adapted for practicing the invention;

FIGURE 3 is a fragmentary sectional detail view similar to FIGURE 1 but showing a modification;

FIGURE 4 shows another modification; and

FIGURE 5 shows a further modification.

Sand molding apparatus utilizing the invention, as shown by way of example in FIGURE 1, comprises a mold assembly which may be a core box including separable bottom and top sections 11 and 12 provided with orientation pins 12 and defining a core-forming cavity 13. Leading into the cavity 13 through the upper or cope section 12 of the core box is a blow hole 14 which has its delivery end opening into the cavity and its upper inlet end, which may be at the upper end of a tubular riser or boss 15, disposed to register with a discharge port 17 in a blow plate 18 forming part of means defining a sand magazine from which molding sand is blown under a substantial pressure head of air with sudden force through the port 17 and the blow hole passage 14 into the cavity 13, air being displaced from the cavity through one or more properly located screens 19.

In order to avoid the sand column in the blow tube passage 14 from drawing out or falling out of the delivery opening inner end thereof when the formed sand core is removed from the cavity 13, a discharge choke comprising a uniformly tapering constriction 20 terminating at the delivery opening is desirably provided on the otherwise uniformly cylindrical wall of the blow hole passage 14. This constriction should be as short and as large as practicable consistent with good performance. For example, about 10 pitch taper in a choke length of about one-half inch has been found highly satisfactory. In producing the choke 20, a cylindrical hole H may be cored or drilled to the smallest constriction diameter. Then this hole is reamed out to the desired cylindrical bore diameter of the blow hole 14, with a nose shape on the reamer having the desired constriction taper by which the choke 20 is formed at the termination of the reaming operation. On the other hand, the choke 20 may be cored directly in the formation of the blow hole 14, or a drill having a pilot end to the shape of the choke constriction may be utilized.

Inasmuch as the forceful delivery of sand through the blow hole 14 has a highly erosive effect on the choke constriction 20 where the core box member 12 is made from the usual material, of which cast iron, steel, aluminum, and like metals are examples, a liner of erosion resistant material, of which certain polymeric materials are examples and cast polyurethane is a preferred material, is provided. Since even a liner of polyurethane will erode after prolonged exposure to repeated sand blowing, the liner is desirable of a replaceable form. To this end, a blow tube 21 having a normal outside diameter substantially the same a the cylindrical diameter of blow hole 14 and of a length at least as long as the blow hole and with a normally cylindrical inside diameter (FIG. 2) is provided. Such a blow tube is easily manufactured at low cost from castable polyurethane which in the set condition is of a stiffly resiliently yieldable character and is highly abrasion resistant, is possessed of high impact strength, but may be readily cut with a sharp instrumenL'A wall thickness of about to /e inch has been found satisfactory in practice. Assembly of such blow tube 21 into the blow hole 14 is readily effected by inserting it from the entry or outer end toward the cavity 13 and on reaching the choke constriction 20 forcing the tube as by pounding it inwardly until its inner end portion conforms to the constriction 20 and completely lines the same, providing the conforming lining and restriction 20a on the inner surface of the inner or terminal end portion of the tube. To ease driving in of the tube 21 and to facilitate the contracting, cramping, compressing action of the constriction 20, a lubricant, such as water, oil, silicone, grease or the like, may be applied to the outer surface of the tube or to the constriction. Where the blow tube 21 is longer than the blow hole 14, so that after the outer end of the tube has been driven to its limit, there is a substantial terminal portion of the blow tube extending beyond the surface contour defining cavity 13 as indicated in dashed outine in FIG.

1, such pro ection may be trimmed off with a sharp instrument.

As a drive-in stop and sealing cushion, the outer end portion of the blow tube 21 may be provided with a lateral flange 22 which in the assembly may be received within a counterbore 23 about the other or outer end of the blow hole 14, with a slight projection of the flange above the end of the tubular boss 15 for engagement sealingly with the blow plate 18 about the port 17. If preferred, of course, the flange 22 may be omitted and the wedging, shouldering coaction of the rigid, fixed constriction 20 on the core box with the choke restriction 20a of the replaceable blow tube being relied upon to retain the blow tube against axially inward displacement or blowout by the air and sand stream during core blowing operation. When desired, the blow tube 21 may be readily replaced by driving it out of the blow hole 14. It will be appreciated that through this arrangement a few standardized lengths and diameters of the blow tube 21 will suffice to take care of at least a large normal range of practical core box requirements.

For equipping a blow hole with a lined choke according to the principles of the present invention, where the blow hole is straight through cylindrical, as for example in an existing core box, or where it would be impractical, or at least inconvenient, to preform the orifice end of the blow hole with a constriction solid in one piece with the box, the technique illustrated in FIGURE 3 may be employed. In this instance, the core box 12 has leading into the cavity chamber 13 the blow hole 14 which is cylindrical straight through from its entrance to its discharge orifice. To provide the tapering constriction 20- an annular insert of generally wedge-shaped construction complementary to the cylindrical diameter of the blow hole is mounted in the orifice end portion of the blow hole and provides the constriction 20, feathering at its inner end to a knife edge joining the cylindrical wall of the blow hole in a substantially smooth merger so that the replaceable blow tube 21 can be forced onto the constriction to provide the choke restriction liner 20a with the same efiiciency as where the constriction 20' is a direct continuation of the wall of the blow hole a in FIGURE 1. Since the blow tube wall is of substantial thickness, it may be relied upon without an encircling boss or other tubular reinforcement, if preferred, as shown in FIG. 3.

Construction of the constriction insert 24 may be in any number of different ways. For example, it may be made as a preformed metal or rigid plastic annulus of wedge cross section to be driven into the orifice end of the blow hole 14 since its thickest section outer or blunt end aifords substantial impact surface for application of a driving tool. The insert may be of greater length and thus greater terminal thickness than would normally be necessary to facilitate the driving in, and the surplus or extra length, as indicated in dashed outline, trimmed off together with the extra restriction end terminal portion of the blow tube. Alternatively, the insert 24 may be molded in situ from a hard setting, firmly bonding epoxy or other moldable plastic with or without fillers such as metal pOWder. A material especially suitable for the purpose comprises a quick setting polyester compound, commercially available under the trademark Dike-O- Plastic.

Instead of driving an insert into the normal diameter of the blow hole, the arrangement of FIGURE 4 may be used, in which the core box 12 ha leading into the coremolding cavity 13 the blow hole 14, in this instance extending through the boss 15 and having at its orifice end a counterbore 25 into which is threadedly secured a constriction insert 27 which may be formed from any suitable material such as metal or hard plastic to provide the rigid tapered constriction 20 having it inner end merging with the cylindrical wall of the blow hole. Thereby, similarly as in the other forms of the invention described, the blow tube 21 is adapted to be driven through the blow hole 14 and the inner end of the blow tube is compressed by the constriction 20 to provide the liner restriction 20a. If desired, any projecting portions of the insert 27 and the blow tube, depicted in dashed outline, may be trimmed off, or if unobjectionable so far as the surface of the core is concerned, may remain.

In FIGURE 5 is depicted an arrangement wherein the core box 12 has the blow hole 14 leading thereinto provided by a separately formed metal tube 28 which has an externally reduced diameter end portion 29 received in a mounting hole 30 formed in the core box, with a shoulder 31 on the metal tube seating about the hole 30. At the inner end portion of the blow hole 14, the tube 28 is provided with the tapered constriction 20. In this arrangement, the blow tube 21 is driven through the blow hole 14 and the tube 28 and through the constriction 20 to provide the choke restriction 28. The terminal end portion of the tube 21 projecting inwardly beyond the constriction orifice may be trimmed off or, as shown, left in place where a dimple in the surface of the core is not objectionable.

In all forms of the invention the orifice end of the restriction of the blow tube pinches off the blow tube sand column at/or in the core surface, whereby that surface is substantially clean when the core is removed from the core box.

It will be understood that variations and modifications may be effected without departing from the spirit and scope of the novel concepts of this invention.

I claim as my invention:

1. In a sand molding apparatus of the character described for use with means defining a sand magazine having a port from which sand is blown under substantial air pressure, a mold member having a molding cavity therein and a blow hole communicating at one end with said port and at the opposite end defining an orifice into said cavity,

a tapered rigid constriction defining said blow hole adjacent to and terminating at said orifice, said constriction comprising an insert in the blow hole having an inner end merging smoothly with the bore of the blow hole, and a replaceable formed liner in said blow hole at least on and conformed to said constriction and defining the actual orifice opening, said liner comprising a highly abrasion resistant material.

2. Apparatus as defined in claim 1 in which the blow 'hole is of substantially uniform diameter throughout its length.

3. Apparatus as defined in claim 1 in which said mold member has a counterbore at the cavity end of said blow hole, and said insert is secured in said counterbore.

4. In a combination according to claim 1, the material of the blow tube being cast polyurethane.

5. Apparatus as defined in claim 3 in which the counterbore at the cavity end of said blow hole has threads, and in which said insert has threads for engagement with the threads of the counterbore.

6. Apparatus as defined in claim 1 wherein said liner comprises a stifily resilient yieldable high impact strength material.

References Cited UNITED STATES PATENTS 2,553,626 5/ 1951 Barlow 164-200 2,637,881 5/ 1953 Peterson 164-200 3,104,432 9/ 1963- Peterson 164-200 J. SPENCER OVERHOLSER, Primary Examiner ROBERT D. BALDWIN, Assistant Examiner US. Cl. X.R.