US2671936A

US2671936A - Die casting machine

Info

Publication number: US2671936A
Application number: US167575A
Authority: US
Inventors: Sundwick Andrew William
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1950-06-12
Filing date: 1950-06-12
Publication date: 1954-03-16
Anticipated expiration: 1971-03-16
Also published as: DE876576C

Description

March 1954 A. w. SUNDWICK DIE CASTING MACHINE Filed June 12, 1950 Patented Mar. 16, 1954 DIE CASTING MACHINE Andrew William Sundwick, Dearborn, Mich., as-

signor to General Motors Corporation, Detroit, Mich., a corporation of Delaware I Application June 12, 1950, Serial No. 167,575

Claims.

This invention relates to improvements in die casting machines and particularly to an insulation construction positioned within a die block of a die casting machine for thermally insulating the die blocks from the nozzle.

The principal object of the invention is to provide a device for thermally insulating the heated nozzle of a die casting machine from the cooled die blocks so as to prevent rapid heat flow from the former to the latter and thereby materially aid in creating a sharp temperature drop between these members. This is accomplished, in accordance with the present invention, by the positioning of an insulating structure within an opening in the stationary die block. A washer of insulating material is supported between metallic structural members, the construction providing only a very small area of metal-to-metal contact between the die block and the portion of the insulating structure which contacts the hot nozzle. Such a construction permits the nozzle to remain hot and the die blocks to remain relatively cool, thereby providing the necessary fluidity of the metal in the gooseneck-to-die passage and also providing the requisite lower temperature of the die blocks to insure proper solidification of the casting in the die cavity or cavities.

A further object of the invention is to provide such an insulating means, located as aforementioned, which is of sturdyconstruction and which is easily assembled and disassembled. The present invention features an insulation construction which will not be readily displaced during operation and which possesses sufficient structural strength to prevent its being crushed under the high compressive stresses to which it is necessarily subjected during operation. Moreover, the insulation construction involved in this invention is so formed and arranged as to prevent leakage of the molten metal between the insulating means and the nozzle or between the insulating means and the adjacent stationarydie block.

Other objects and advantages of the invention will more fully appear from the preferred embodiments of the invention illustrated in the accompanying drawing, in which:

Figure l is a fragmentary longitudinal sectional view, with parts in elevation, of a die casting machine embodying the invention;

Figure 2 is an enlarged fragmentary sectional view of a stationary die block enclosing the heat insulating construction shown in Figure 1;

Figure 3 is a fragmentary sectional view of a modification of the die block and insulation construction shown in Figures 1 and 2. 7

Referring more specifically to the drawing, a melting pot H] of a type commonly employed in commercial die casting machines is shown in Figure 1. This pot contains a supply of molten die casting metal I2 and forms a part of a furnace, indicated generally by I 4, which may be fired by a gas burner or other suitable means. Suspended within the melting pot I0 is a onepiece iron casting l6 having a vertically extending cylindrical bore which forms a pressure chamber I8. A hardened cylindrical liner or sleeve 20 is shown as shrink-fitted within the bore and welded to the upper end of the casting I6 by welds 22. The liner and side wall of the casting have registering openings forming an intake port or passage 24 for entry of molten metal from the pot to the interior of the pressure chamber.

In cooperative relation with the inner walls of the liner 20 in the pressure chamber l 8 is a reciprocatory plunger or piston 26 formed of any suitable material and shown as having its lower end grooved and provided with a plurality of hardened steel split piston rings 28. Reoiprocation of the plunger is accomplished by securing the upper end thereof to a connecting member 30 which is attached to a suitable mechanical or fluid pressure driving means, such as an air cylinder, not shown, mounted on vertical support members 32.

A skirt or shield 34 mounted on the casting [5 over the intake port 24 causes the molten metal in the melting pot to be drawn into the pressure chamber from the bottom of the pot to avoid undue agitation of the molten metal and to prevent dross from the surface from entering the pressure chamber when the level of the molten metal is allowed to fall.

The casting It has an elongated throat or gooseneck passage 36 leading from the bottom of the pressure chamber is and extending upwardly therefrom for conveying the molten metal, the lower end of the steel liner 20 having an opening 38 registering with the lower end of the gooseneck passage. The outlet end of this passage communicates with a nozzle 40 through an opening 42 in a nozzle seat or spacer 44 of hardened steel, which is fitted into the upper end of the gooseneck and serves to interconnect the entrance end of the nozzle with the gooseneck passage. The spacer 44 is adapted to fit against the inlet end of the nozzle 4|! by the provision of a cup-shaped recess in its adjacent face.

The nozzle 40 having a longitudinal passage 4| extending axially therethrough is shown as extendingthrough a generally frusto-conical open- 3 ing 46 in a stationary platen 48. Abutting the platen and secured thereto is a stationary die block 50, which is provided with a longitudinally extending opening 52 registering with the opening 46 in the platen. An insulating structure, indicated generally by 54, is fitted within the stationary die block opening 52 and completes the stationary die assembly. The structure shown in Figures 1 and 2 is in the form of a watercooled insulated sprue bushing, the construction details of which will be subsequently described.

In order to insure free flowing of the metal and its retention in a fluid condition until it arrives even at distant parts of the mold cavity, the nozzle 40 may be separately heated by any suitable means, such as a wide ring burner 56. Since the insulating structure insures that the high temperature of the nozzle 40 shall not unduly heat the stationary die block 52 itself, the absorption of heat from the casting by the die block is not interfered with.

On a movable platen or die holder 58 secured to a slidable carriage, not shown, is mounted a suitable movable die block 60 adapted to mate with the stationary die block 50 to define the die cavity or cavities, also not shown. A die core or sprue spreader 64 is fitted in a recess in the working face of the stationary die and shown as secured thereto by a suitable set screw 66.

The tapered, rounded end of the sprue spreader,

which projects into the sprue 68 within the stationary die assembly to form an internal molding surface, may also be water-cooled to provide for more rapid cooling of the casting in the sprue.

The supporting and actuating mechanisms for the movable die are not shown in complete detail herein since they form no part of the invention, it being sufficient to state that the various portions of the die blocks and their actuating mechanism are supported in position to permit reciprocation of the die holder 58 supporting the movable die block and of an ejector supporting plate I on which are mounted the ends of ejector pins 12. These movable members are adapted to be' reciprocably driven by any suitable mechanical or fluid pressure means, not shown.

After the die blocks are closed, molten metal from the pot I0, entering the pressure chamber through the passage 24, is forced by the reciprocatory plunger 26 through the gooseneck 36, through the passages 42 and M in the spacer and nozzle, respectively, through the sprue 68 and into the passages or runners B2 to the die cavities. Upon solidification of the die casting metal, the die blocks are separated and the ejector ins are advanced to force the castings out of the movable die 58 and off the core 64, after which the gate is usually removed manually. The die blocks are then closed and the cycle repeated. In the form shown in Figures 1 and 2, the insulating structure 54, hereinbefore mentioned, is in the form of an assembly which includes a sleeve or insert 14 fitted into the opening 52 in the stationary die block 50. This sleeve is provided with an outwardly extending flange 16 which abuts a shoulder I8 on the die block to prevent axial movement of the sleeve relative to the die block. A preferably cylindrical extension 80 of the sleeve, shown with a reduced diameter, projects axially toward the nozzle 40. Fitted around the extension 00 of the sleeve and having an edge abutting the larger face of the flange I6 is shown an annular collar 82, which may be secured to the sleeve by welding, as indicated by 84. This collar has its face nearest the nozzle provided with an annular recess 86 having a base in the same plane as the adjacent end face of the sleeve I4 for seating a preferably annular insulating washer 88 of mica or other suitable insulating material. This insulating washer, therefore, abuts not only the adjacent end face of the collar but also a portion of the end surface of the sleeve extension 80.

As shown in Figures 1 and 2, water or other fluid cooling of the sprue bushing may be provided for by forming a portion of the inner peripheral surface of the collar 82 with a groove to define, together with extension 80, an annular passage 90. Cooling water may be forced through this passage to further contribute to the rapid temperature drop in the metal flowing from the heated nozzle to the die cavities.

While the sleeve 14 and the collar 82 are shown as formed in two parts, it will be appreciated that some of the functions of the invention could be performed if these parts were made integral, the coolant passage, if desired, being formed by a separate machining operation.

The insulating washer 88 is clamped in position by a metallic retainer plate 92, preferably cylindrical in shape and provided with a generally central opening, which plate is shown as secured to the collar 82 by welds 94. The inner face of this plate has an axially projecting shoulder 95 adjacent the sprue positioned within a recess 88 in the end of the sleeve I4 and abutting the base surface thereof. The peripheral surface of the shoulder 96 positioned against the side walls of the recess 98 in the sleeve further aids in maintaining radial alignment of the plate 92 relative to the sleeve as well as positioning the insulating washer 88. Moreover, the extension '14 serves to seal the insulating washer from the sprue, thereby preventing seepage of the molten die casting metal I00 in the sprue into the insulating washer under high die casting pressures, which seepage would cause rapid deterioration of the washer. The intake face of the retainer plate 10 is provided with a concave recess I02 into which is seated the rounded outlet tip of the nozzle 36.

Fastening means, such as a screw I04, provided with a washer I 06 which overlaps a recessed portion I 08 of the outer end face of the retainer plate 92, may be employed to prevent axial movement of the insulated sprue bushing toward the nozzle.

Referring to the insulating construction shown in Figure 3, the stationary die block I50 has its intake face provided with a recess I52, preferably of a generally cylindrical shape. Positioned within this recess and seated against the base thereof is a relatively thin washer I88 of mica or other suitable insulation material. This insulating washer is provided with a central aperture I90 which registers with a longitudinally extending opening I92 in the die block I50.

Also located with the recess I52 is a metallic retainer plate or bushing I 94 having one face abutting the insulating washer I88 and its opposite face preferably provided with a concave recess I93 for seating the rounded tip of the nozzle 40. The plate I94 is preferably annular and provided with a central aperture I98 registering with the aperture I90 in the insulating washer I88 and with the opening 4| in the nozzle. This plate may be advantageously constructed of hardened steel with its outer peripheral edges tapered to provide practically only line contact between these edges and the side walls of the die block recess I52, as indicated at 198.

A securing device, such as a screw 200, may e used to retain the retainer plate in position, this construction permitting the ready removal of the plate for replacement of the insulating washer 88.

t will be noted that, inasmuch as the insulating Washer extends completely to the sprue passage ISQ-Jlit-Illt, the construction shown in Figure 3 results in minimum metal-to-metal contact between the plate I94, which is in heat conductive contact with the hot nozzle 40, and the stationary die block I50. Furthermore, an annular groove 292 may be provided in the inner face of the metal plate I94 to also reduce the area of contact between the plate and the insulating washer. A small annular contact surface 29 on the same face of the plate near its outer edges is desirable to insure flush seating of the plate and to enable it to withstand the high compressive stresses to which it is subjected during operation.

It can be seen, therefore, that this structure effectively thermally insulates the nozzle from the die, the axial passage of heat from the former to the latter being prevented by the insulating washer I88. Heat is also prevented from being transmitted radially from the retainer plate I94 to the die block because of the small area of contact between these members, the generally annular spaces 296 functioning as insulating spaces. The small additional contact area between metallic surfaces resulting from the presence of the screw 200 does not materially affect the efiiciency of this insulating structure.

It will be noted that the danger of the molten metal, while under pressure, seeping into the in" sulating washer I98 is substantially reduced in this modification shown in Figure 3 by having thea plate ass extend radially into the sprue toa greater extent than does the insulating washer, as indicated at 298. The offset thereby provided prevents the washer from being subjected to the dynamic pressure of the flowing molten metal.

While the described embodiments of the present invention constitute preferred forms, it is to be understood that other modifications and variations in details of structure and arrangement may be made without departing from the scope of the invention as defined in the appended claims.

I claim:

1. In a die casting machine having a movable die block and a cooperating stationary die block with an opening extending therethrough for receiving molten die casting metal from a nozzle, an insulating structure fixed within said opening for thermally insulating the die blocks from the nozzle, said insulating structure comprising a metallic plate member and a washer of insulating material having one face abutting supporting surfaces of the stationary die assembly and its opposite face abutting the plate member and secured thereby, said plate member having its face remote from the washer recessed for seating the tip of the nozzle, said washer and plate member provided with registering openings for the conveyance of molten metal therethrough.

2. In a die casting machine having a die block with an opening extending therethrough for receiving molten metal from an end of a nozzle, an insulating assembly fitted within said opening and comprising a metallic sleeve, a metallic collar member surrounding said sleeve and defining with it a passage for the circulation therethrough of a fluid coolant, a metallic retainer plate positioned between the nozzle and the collar member and sleeve and having one face provided with a recess for seating the end of the nozzle, and a washer of insulating material supported between the other face of the retainer plate and the adjacent end faces of the collar member and sleeve for thermally insulating said collar member and said sleeve from said plate, said sleeve, retainer plate and washer being provided with generally aligned openings for receiving molten metal from said nozzle.

3. In a die casting machine having a movable die block and a cooperating stationary die block with an opening extending therethrough for receiving molten metal from a nozzle, an insulating structure fixed within said opening for thermally insulating the die blocks from the nozzle, said insulating structure comprising a washer of insulating material having one face abutting a portion of the walls of the stationary die block opening and a metallic retainer plate having its peripheral edges tapered outwardly and contacting the walls of the stationary die block opening, said plate having one face abutting said washer for the securing thereof and its opposite face provided with a recess for seating the tip of the nozzle, said washer and plate being provided with registering openings for the conveyance of molten metal therethrough.

4. In a die casting machine having a die block with an opening extending therethrough for receiving molten metal from a nozzle, a metallic member positioned within the opening having one face in direct heat conducting relation with the tip of said nozzle and having a passage for receiving molten metal from said nozzle, and a member of insulating material having a corresponding passage abutting the opposite face of said metallic member for thermally insulating the die block from the metallic member.

5. In a die casting machine having a die blocl: with an opening extending therethrough for receiving molten metal from a nozzle, a metallic sleeve positioned within said opening, a layer of insulating material for thermally insulating the die block from the nozzle also located within said opening and abutting one end of said metallic sleeve, and a metallic plate having one face positioned against the layer of insulating material and its opposite face in direct heat conductive relation with the tip of said nozzle, said metallic sleeve, plate and layer of insulating material being provided with registering openings for conveying molten metal from the nozzle.

ANDREW WILLIAM SUNDWICK.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,458,482 Grey June 12, 1923 1,673,838 Lester June 19, 1928 1,948,992 Morin Feb. 2'7, 1934 1,952,201 Flammang et al. Mar. 27, 1934 2,000,488 Korsmo May '7, 1935 2,058,378 Freund Oct. 20, 1936 2,242,350 Eldred May 20, 1941 2,413,401 Youngblood et al. Dec. 31, 1946 FOREIGN PATENTS Number Country Date 598,045 Great Britain Feb. 9, 1948