US2777166A - Method of forming die cast products on pre-die cast and remeltable cores - Google Patents

Description

Jan. 15, 1957 H. MORIN 2,7

METHOD OF FORMING DIE CAST PRODUCTS ou PRE-DIE CAST AND REMELTABLE CORES Filed April 23, 1952 2 Sheets-Sheet 1 *INVENTOR 2| LOUIS H MORIN I v ATTOR EY 7 Jan. 15, 1957 H. MORlN METHOD OF FORMING DIE CAST PRODUCTS on PRE-DIE CAST AND REMELTABLE CORES 2 Sheets-Sheet 2 Filed April 23, 1952 INVENTOR LOUIS H. MORIN ATTO R EY Unite States Patent IVIETHOD OF FOG DIE CAST PRODUCTS ON PRE-DIE CAST AND REMELTABLE CORES Louis H. Morin, Bronx, N. Y.

Application April 23, 1952, Serial No. 283,916

Claims. (Cl. 18--59) This invention relates to the formation of molded or die cast products in pressure injection of molding or casting material simultaneously into spaced cavities of a pair of dies to form, in a successive series or operations or injections, a molded or cast product on premolded or cast cores and, then, in removing or separating the cores from the product and remelting the same. Still more particularly, the invention deals with a method of the character described which facilitates the formation of what is generally referred to as undercuts in a product or a cored portion of a product.

The novel features of the invention will be best understood from the following description, when taken together with the accompanying drawing, in which certain embodiments of the invention are disclosed and, in which, the separate parts are designated by suitable reference characters in each of the views and in which:

Fig. 1 is a diagrammatic face view of one die of a pair of dies illustrating spaced cavities of the dies and the united members formed in each injection charge of molding or casting material into said cavities.

Fig. 2 is a view, similar to Fig. 1, showing only a part of the construction and illustrating parts in a different position.

Fig. 3 is a view similar to Fig. 2 showing anotherportion of the die in the same position of the parts as shown in Fig. 2.

Fig. 4 is a diagrammatic view illustrating a stripping I Fig. 8 is a partial section on the line 88 of Fig. 7; and i Fig. 9 is a schematic perspective view illustrating a detached core of one part or product, and including the integral cores of the adjacent part but omitting said adjacent part from the showing.

In the production of molded or die cast products, considerable expense is required in producing and maintaining cores utilized in the formation of molded or cast products of various types and kinds and, as these cores are susceptible to breakage in handling or otherwise, the cost of maintaining such cores is a considerable factor. Furthermore, in many instances, it is desirable to produce molded or die cast products having undercut surfaces which have been impossible to form with normal type of coring; thus it has been necessary to revise the design of the product or alter the method of its production in order to produce the desired result.

It is the purpose of my invention to provide a method which will materially minimize the cost of producing molded or castproducts of the character described by dispensing with the use of the conventional permanent cores "Ice and, further, it is possible to form the difiicult undercut surfaces of molded or cast products by a method which comprises first molding or casting the core, or cores, to be employed and, then, molding or casting the resulting product around such cores and, then, removing the cores from the resulting product and returning the same' to the pot or heated zone for remelting or reconversion to the molding or casting material employed.

By virture of this method, a solution is now available for the many problems which'have presented themselves over the years in connection with the production of molded or cast products. In Figs. 1 to 6, inclusive, I have shown, by way of illustration, one adaption of my invention, wherein two cores are molded or cast one upon the other and, then, a product is molded or cast on the united cores, after which said united cores are removed from the product and remelted.

In said figures, the interunited or united cast cores are formed in two stations or cavities of a pair of dies; whereas, in Fig. 7 of the drawing, I have shown united cores formed in spaced cavities of a single station of the die but, in both instances, the cores are utilized to form cored or undercut portions of the resulting product and are then simultaneously removed from the product.

In Fig. 1 of the drawing, I have illustrated at 15 one die of a pair of dies, on the face of which are formed three cavity stations 16, 17 and 18, the three stations being joined to a main sprue or gate 19 by branch sprues or gates 20, 21 and 22. In this connection, it will be understood that at least part of the gate 21 will be formed in a cavity or recess on the surface of one die; whereas, the gate 22 will be formed in a corresponding recess or cavity of the other die so that these gates will cross, as at 23, between the cavity stations 17 and 18. The surface of the die 15 also has two vertical bores 24 and 25 in which are arranged transfer pins 26 and 27.

Part of the gate 19,'as at 19', encircles the pin 26 whereas part of the casting of cavity 17 extends to form a ring 28 on the pin 27. The dies are also recessed to form stripping shoulders 29 and 30 in stripping the castings from the pins, as later described. Supported below but in close proximity to the dies are a pair of separating or stripping tools 31 and 32, note Figs. 4, 5 and 6. These tools have yoke or jaw ends, as at 33 and 34, to engage cores in the operation of removing or stripping the same from the resulting product, as later described.

Formed in the cavity 16 is one fork-shaped or yokeshaped core part 35 having curved recessed sides 36 and a channel 37 of said core has a reduced and rounded inner recess 38. At 39 is shown a portion having, at its outer end, a T-head 40 or, in other words, this head has laterally extending flanges to be engaged by the yoke or jaw end 33, as clearly noted in Fig. 6 of the drawing.

In the cavity 17 is formed the associate core part 41, which comprises a tongue member 42 extending into the recess or channel 37 and has, at its inner end, a V-notch 43. At the base of the tongue is an enlargement 44 which servesto finish the end of the cast product 45 formed in the cavity 18, the product in the construction shown being the slider of a separable fastener. The core 41, or the extending part 46 thereof, includes a T-head 47, generally like the head 40 and which is adapted to enter the channel or jaw end 34, as noted in Fig. 6. The cavity 18 of the dies which are employed, and only one of which is shown in Fig. 1 of the drawing, is shaped to form the upper and lower walls 48 and 49 of the slider 45, note Figs. 5 and 6, the upper wall having the projecting U-shaped pivot bearings 50 and the elongated aperture 51.

The walls 48 and 49 are joined by the usual connecting- Web 52, this web being formed between the recess 38 and notch 43; whereas, the curved wall portions 39' of the part 39 form the curved end walls 53 of the slider I It will also be noted that the tongue 42 is formed with projecting lugs 54 adjacent the part or shoulder 44 to continue the formation of the channel 55 in the slider and the recesses 56 between the flanged side walls of the slider 45 as noted in Fig. .6. It will be understood, in this connection, that the core 35, in .combinatiouwith the core 41, otherwise completes the formation of this channel, when the cores are separated from the resulting product, as illustrated in Figs. 5 and 6 of the drawing. For purposes of description, 35 and 41 generally can be identified as the associated and united core parts.

The method will be clearly understood from the foregoing description, when taken with :the accompanying drawing and the following statement.

The heated material utilized in forming the molded or cast products will be pressure injected, from a .suit able source, not shown, through a nozzle indicated in part at 57 in Fig. 1 of the drawing. This material passes through the gate 19 into the gates 20, 21, forming the castings in the cavities 16 and 17, into the extension 58 of cavity 17 forming the ring 28, through the gate 22 into the cavity 18. It will, thus, be seen that, in each pressure injection of the molding material, a molded or cast part is formed in each of the cavities. Upon completing this operation, the dies are opened and the two pins 26 and 27 are moved downwardly to bring the core 35 into the cavity 17, the united cores 35, 41 into the cavity 18, and the assemblage comprising the cores 35, 41 and the product 45 beyond the limits of the dies into position between the stripping or separating tools 31, 32 shown in Figs. 4 to 6, inclusive. The dies are then partially closed, the pins 26 and 27 stripped from the ring portions 19', 28 and returned to the position shown in Fig. 1 of the drawing; whereupon, the dies are again closed and the second successive injection takes place.

In this second injection, another core 35 is formed in cavity 16, another core 41 is formed on the first core 35 positioned in the cavity 17, and a product 45 is formed on the united cores 35, 41 positioned in the cavity .18. Then again, the dies will be opened, the pins 26, 27 operated and the above operation repeated, returning the pins to the normal station and finally a third charge is injected into the dies, again resulting in the formation of the cast parts 35, 41, 45 in the manner previously described.

In these successive molding or casting operations, the tools 31 and 32 are actuated by siutable means, not shown, to move these tools in opposite directions, thus severing the cores 35, 41 from each other and from the casting 45, the casting being preferably trimmed prior to this operation at said station to remove the gates 21 and 22 from the parts 41 and 45. The gates 21 and 20 can remain on the part 35, as this part, in its entirety, is returned to the heated zone, or melting pot, for remelting and thus does not require separation.

The result of the foregoing operations will be the production of a finished and trimmed product such, for example, as the slider 45 which will be automatically discharged into a suitable receiver from the separating or stripping station.

It will also be understood that the core 41, including the trimmed gates, are returned to the heated zone or melting zone for reuse.

In Figs. 6 to 9, inclusive, I have shown a modification of the method, wherein, instead of using three cavity stations, as for example, the stations 16, 17 and 18 of Fig. 1, two cavity stations, 59 and 60, are employed in a pair of dies, the face view of one of which is indicated at 61. In this construction, a gate 62 is employed which has branches 63 and 64 leading to spaced cavity portions 65 and 66 at the station 59 and a short, wide branch 67 which leads to the cavity 68 of the station 60. The gate 62 is also shaped to form a ring portion 69 around a transfer pin 70 which operates in a vertical bore 71 formed between the dies.

The cavities 6566, in the construction shown, are generally of the same shape, although they might be of any desired or different shape and these cavities are adapted to form stud portions 72, 73 of core members having substantially rectangular heads 74, 75 with curved adjacent recesses 76 and 77.

The cavity 68 is generally shaped to form a cylindrical product 78 having, centrally of opposed walls, rectangular bearing extensions, as at 79, apertured, as seen at 80. It will also be noted from a consideration of Fig. 7 of the drawing that the bore 81 of the cylindrical product 78 is in alinement with the curved surfaces 76 and 77 of the cores employed.

In Fig. 8 of the drawing, the associate die member 61' is shown in section and, in this figure, a cross-sectional view is shown through the cylindrical product 78 to indicate, in exaggerated form, the taper of the cylindrical product to opposed ends to facilitate displacement of the product from the cavities of the dies. The operation of the method, as disclosed in Figs. 6 to 9, inclusive, will be apparent from the detail description of the operation of forming the product 45 when taken with the following brief statement.

In Fig. 7, it will be apparent that in each injection of the molding or casting material, the two cores are formed simultaneously in the formation of the cylindrical part 78. Then the dies are opened and the pin 70 moves the preformed cores into position within the cavity of the station 60, the pin 70 stripped from the product and returned to its normal position and the second casting is then formed and, in this latter operation, the product 78 is formed around the two cores, the cores forming the bearings 79 as well as the apertures 80. Then,

when the united parts are moved to the trimming or sep arating station, generally identified by the reference character 82, two stripping pins 83 and 84 are employed to strip or eject the cores from the product 78 in the manner diagrammatically illustrated at the lower portion of Fig. 7, in which operation the cores are stripped from the gates 63 and 64 and these cores will be ejected from the product in the manner illustrated diagrammatically in Fig. 9 of the drawing.

During the aforesaid operation, the gate portion 67 can be trimmed from the previously formed casting 78 which would automatically remove the finished casting from the machine and free the entire gate, including the part 62 and ring 69, for movement into a receptacle and this gate, together with the two removed cores, can be remelted for use in forming additional castings.

From the foregoing, it will be understood that, in both procedures, which are diagrammatically illustrated in order to portray the general procedure in carrying out my improved method, precast core members are utilized in forming cored portions and/or undercut portions of a resulting product and are then stripped or separated from the product and returned to the heated or melting zone for reconversion to the molding or casting state. Aside from slight losses that might prevail, it will appear that substantially no loss exists in utilizing the precast cores as a means for forming cored or undercut portions in the cast product to be formed.

It will also be apparent that the entire method is automatic in operation, thus products of the kind under consideration can .be produced at extremely low cost, not only from the standpoint of economy occasioned by utilizing the cores as herein specified, but from the standpoint of obviating the losses and costs occasioned by wear and tear upon permanent cores as used in heretofore or known methods of procedure.

It is generally known in the art that, in forming a cast or molded part or product on a core, shrinkage of the product takes place, which would have the tendency of freezing or seizing the product upon the core; in the past, removal of such a core has been attended by core wear and/ or core damage. In the present invention core wear and/or damage is not a factor because each core is used once and then disposed of or discarded. Thus, even if such force were used to remove the core as would be apt to damage it,this would be of no importance.

However, in the present invention it has also been found that the force required to remove a core is minimized because of the small temperature difference existing between a product casting and the previously formed core casting; these castings are formed at such a high speed that their temperatures may be regarded as substantially the same. For example, the product casting may be formed in a fraction of a second after the core casting. These castings cool at the same rate, and they reach the final stage of cooling at substantially the same time having substantially the same temperature. Thus, no difiiculty is experienced in promptly removing or stripping the core part from the product part at the separating station, as defined.

It will be apparent that the method herein disclosed can be utilized for forming injection molded or die cast products of any type or kind, wherein the desirability of forming cored portions of the resulting product is an important factor, particularly with odd shapes or with the production of undercuts or socket portions, as is illustrated in Figs. 7-9, inclusive. As may also be apparcm, the method is applicable for making castings that require the use of one or more cores, including castings with undercuts.

Having fully described my invention, what I claim as new and desire to secure by Letters Patent is:

1. The method of forming die cast products, which comprises casting two cores for the product to be formed in a pair of cavities of a first cavity portion of a pair of dies, then moving the cast cores to a second cavity portion of the same dies and forming a product on the cores disposed in the second cavity portion, said product partially enclosing the cores and being formed of the same material as the cores, said product tending to exert a shrinkage action on the cores, said cores and product being cast at such a rate that they are at substantially the same temperature in said second cavity portion, said shrinkage tendency being thereby opposed, cooling said cores and product at the same rate so that they reach a final stage of cooling at substantially the same time having substantially the same temperature, forcibly removing the cores as substantially integral pieces from said product, said cores being used only once in said method, as described, and being either discarded or reused as sources of casting material for forming additional cores and products.

2. The method of forming die cast products which comprises first casting cores in a pair of relatively movable dies, then moving the cast cores to another portion of the same dies and casting a complete product on the cores in a single casting step, said product engaging the cores and being formed of the same material as said cores, said product tending to exert a shrinkage action on the cores, said cores and product being cast at such a rate that they have approximately the same temperature during said engagement, cooling said engaged cores and product at the same rate so that they have approximately the same temperature during cooling, and forcibly removing the cores from the product, said cores being used only once in said method, as described, and being either discarded or reused as a source of casting material for forming additional cores and products.

3. Method of claim 2 in which said cores are in contact with one another.

4. Method of claim 2 in which said cores are spaced apart from one another.

5. The method of producing die formed products of the character described, which comprises pressure injecting a moldable material simultaneously into spaced core and product cavities of a pair of relatively movable dies and around a transfer member positioned between said dies, moving said member when the dies are in open position to shift a cast core from the core cavity to said product cavity, closing the dies and stripping the member from said core and returning the same to position to receive a next successive injection of said moldable material, injecting moldable material to said dies to form a product on the core positioned within the product cavity of the same material as said core, said product engaging the core and tending to exert a shrinkage action thereon, said core and product being cast at such a rate that they have substantially the same temperature in said product cavity, said shrinkage tendency being thereby opposed, moving said member to shift the engaged core and product to a core-separating station while allowing said engaged core and product to cool by natural cooling, forcibly removing the core from the product at said station and obtaining said core and product as separate, individual parts, and reusing the core as a source of moldable material for producing additional cores and products.

6. A continuous method for producing die cast sliders which comprises die casting a core in a cavity of a pair of relatively movable dies by injecting molten casting material to said cavity, opening the dies and moving the core to a second cavity therein, closing the dies and casting a second core in contact with said first core while simultaneously casting a third core in the first cavity, forming gripping portions on each of said cores, opening the dies and moving the first and second cores to a third cavity while simultaneously moving the third core to the second cavity, closing the dies and casting a slider onto the first and second cores which slider partially encloses the cores and casting simultaneously with the slider a fourth core in contact with the third core in the second cavity and a fifth core in the first cavity, said cores and slider being formed of the same material and said slider tending to exert a shrinkage action on the cores, opening the dies and discharging therefrom the slider cast about the first and second cores while simultaneously moving the third and fourth cores to the third cavity and the fifth core to the second cavity, engaging the gripping portions of said first and second cores and forcibly withdrawing the cores from the slider, thereby overcoming the effect of said shrinkage action and separating said cores as substantially integral pieces from the slider, reusing the separated core pieces as a source of casting material for producing additional cores and sliders, and continuing to cast a slider in said third cavity onto the previously formed pair of cores therein while simultaneously casting in the second cavity another core in contact with a previously formed core and, in the first cavity, simultaneously casting still another core.

7. A continuous method for producing die cast products which comprises die casting a core in a cavity of a pair of relatively movable dies by injecting molten casting material to said cavity, opening the dies and moving the core to a second cavity therein, closing the dies and casting a second core in contact with said first core, opening the dies and moving the cores to a third cavity, closing the dies and casting a product onto the cores, said cores and product being formed of the same material and said product tending to exert a shrinkage action on the cores, opening the dies and discharging the product and cores therefrom, forcibly withdrawing said cores from the product, thereby overcoming the effect of said shrinkage action and separating said cores as substantially integral pieces from the product, and reusing the separated core pieces as a source of casting material for producing additional cores and products.

8. A continuous method for producing die cast products which comprises die casting at least one core in a cavity of a pair of relatively movable dies by injecting molten casting material to said cavity, moving the core to a second cavity in said dies and casting in a single injection step a complete product thereon which engages the core, said core and product being formed of the same material and said product tending to exert a shrinkage action on the core, said core and product being cast at such a rate that they have substantially the same temperature in said second cavity, said shrinkage tendency being thereby opposed, allowing said engagedcore and product to cool by natural cooling, forcibly separating the core from the product, thereby overcoming the effect of said shrinkage action and obtaining said core and product as separate, individual parts, said core being used only once in said method, as described, and being either discarded or reused as a source of casting material for forming additional cores and products.

9. A continuous method for producing die cast products having a cored portion which comprises die, casting a core in a pair of relatively movable dies, casting a product of the same material as the core in contact with and engaging said core, thereby shaping the product and forming said cored portion therein, said product tending to adhere to the core by exerting a shrinkage action on the core, casting said core and product at such a rate that they have substantially the same temperature during said engagement, thereby opposing said shrinkage tendency, cooling said engaged core and product at the same rate so that they have substantially the same term perature during cooling, separating the core from the product by forcibly overcoming the adherence therebetween due to said shrinkage action, said core being used only once in said method, as described, and being either discarded or reused as a source of casting material for forming additional cores and products.

10. A continuous method of producing die castings each comprising at least two parts which comprises casting a first part in a pair of relatively movable dies, casting a second part of the same material as the first part in contact with said first part, thereby shaping the sec- 0nd part, said parts tending to adhere to each other by virtue of a shrinkage action arising therebetween, said parts being cast at such a rate that they have approximately the same temperature during said contact, thereby opposing said tendency to adhere, cooling said parts at the same rate so that they have approximately the same,

temperature during cooling, separating said parts by forcibly overcoming the adherence between them due to said shrinkage action, thereby obtaining said parts each as a separate, individual piece, and casting successive parts one in contact with another and separating the adhering parts, as described.

References Cited in the file of this patent UNITED STATES PATENTS 2,017,216 Marcus Oct. 15, 1935 2,234,185 Marinsky et a1 Mar. 11, 1941 2,266,433 Morin et al. Dec. 16, 1941 2,569,083 Wilhelm Sept. 25, 1951 2,577,350 Morin Dec. 4, 1951

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