US2837795A

US2837795A - Die casting structure

Info

Publication number: US2837795A
Application number: US587793A
Authority: US
Inventors: Ring Lucian
Original assignee: RING ALUMINUM DEV Co
Current assignee: RING ALUMINUM DEV Co; RING ALUMINUM DEVELOPMENT Co
Priority date: 1956-05-28
Filing date: 1956-05-28
Publication date: 1958-06-10
Anticipated expiration: 1975-06-10

Description

June 10, 1958 L. RING on: CASTING STRUCTURE 2 Sheets-Sheet 1 Filed May 28, 1956 INVENTOR. LUOIAN RING NmTLuD mN ATTORNEYS June 10, 1958 L. RING 2,837,795

DIE CASTING STRUCTURE Filed; May 28, 1956 2 Sheets-Sheet 2 g g (\l g 2 (\l (O.- l 1 g N '2. 3 I

I0 \I A 8, n co 2 INVENTOR. LUCIAN RING mwa ATTORNEYS casting machine.

United States Patent DIE CASTING STRUCTURE Lucian Ring, Birmingham, Mich, assignor to Ring Aiuininurn Development Company, Clawson, Mich, a corporation of Michigan Application May 28, 1956, Serial No. ssmss s (llaims. (Cl. 22-40 This invention relates to die casting structure and refers more particularly to structure for supplying the m ectmg apparatus of a die casting machine with molten casting material from a reservoir.

in die casting structures of the type involved herein, injecting apparatus is employed to inject casting material into a die and a reservoir provides a source-of supply for the casting material. In accordance with customary practice, means are provided for supplying casting material from the reservoir to the injecting apparatus, and such means comprises a fluid displaoement device ex tending into the reservoir and beneath the level of the casting material therein. The displacement device is provided to pump casting material into the injecting apparatus, and prior to the operation of the displacement device, casting material is admitted thereinto to the level of casting material in the reservoir. It will be apparent that changes in the level of casting material in the reservoir will result in changes in the volume of casting material admitted to the displacement device and corresponding changes in the volume of casting material delivered to the injecting apparatus.

The displacement device is initially adjusted to supply the injecting apparatus with a predetermined volume of casting material sufficient to completely fill the die and to leave a relatively small slug or biscuit. If the volume of casting material supplied to the injecting apparatus is too small, there is the possibility that the die will not be completely filled. If the volume of casting material supplied to the injection apparatus is too large, the size of the v biscuit will be excessive. An oversized biscuit also has definite drawbacks. The reason for this is that when the die is opened and the pressure on the cast article and on the biscuit is removed, the central portions of the biscuit may still be in a molten condition although the outer shell of the biscuit has solidified. In oversized biscuits, the shell may not have solidified to a thickness suflio'ient to contain the molten interior so that when the pressure is released, the biscuit will burst or explode. An oversized biscuit may be compensated for by retarding the cycle of operation so that sufficient time is allowed forthe biscuit to harden from the outside inwardly to a point where no explosion will occur. However, there are obvious drawbacksto slowing down the cycle of operation.

The level of molten casting material in the reservoir will, of course, change during the operation of the die As casting material is continuously being used, the level will decrease. 0n the other hand,

the casting material in the reservoir is replenished at intervals to restore the level. The reservoir will usually be heated by an electric induction furnace, and it has been noted that the level of casting material in the furnace will rise when the current comes on.

- One object of this invention is to provide means for supplying casting material from the reservoir to the injecting apparatus of a die casting machine in which changes in the level of tl e casting material in the reserice 2 v-oir will not materially affect the volume of casting material supplied to the injecting apparatus.

Another object of the invention is to provide means for supplying casting materi' i from the reservoir to the injecting apparatus including a fluid displacement device or pumping assembly extending into the reservoir beneath the level of the casting material therein, having a fluid passage extending from the pumping assembly upwardly above the level of casting material for communication with the injecting apparatus, and means for admitting casting material from the reservoir to the pumping assembly to fill the pumping assembly and passage to the level of casting material in the reservoir, the passage being of a size such that changes in the level of casting material in the reservoir along the passage will result in relatively small changes in the volume of casting material so admitted as compared to the displacement of the pumping assembly and so will not materially affect the volume of casting material pumped to the injecting apparatus by the pumping assembly.

These and other objects of the invention will become apparent from the following description taken in connection with the accompanying drawings, wherein:

Figure l is a fragmentary side elevational view,'partly in section, of die casting structure embodying the invention;

Figure 2 is an elevational view, partly in section, looking toward the right in Figure 1;

Figure 3 is an enlarged elevational view, partly in section, of a portion of the apparatus shown in Figure 2;

Figure 4 is a top plan view of the displacement device; Figure 5 is a detail sectional view of a portion of Figure 1;

Figure 6 is similar to Figure 3 and illustrates a modification.

Referring now more particularly to the drawings, and especially to Figures 1-5, the apparatus comprises a stationary support or platen it having a stationary die part 12 secured thereto. A movable die part 14 is provided which is movable toward and away from the stationary die part. Movable die part 14 is carried by a carrier 15 slidable on rods 16 secured to platen 10. The carrier may be reciprocated by any suitable means (not shown) to move the die part 14 toward and away from the stationary die part 12. The adjacent surfaces of the die parts engage each other in the closed position of the die illustrated and are formed with registering recesses to define the die cavities 18. Molten casting material which may, for example, be of the lightweight non-ferrous type, such as aluminum or magnesium, is introduced into the die cavities by injecting apparatus indicated generally at 20. The injecting apparatus includes an injecting cylinder 22 which ex tends through and is secured to platen 10 and projects therebeyond through the hired die part 12 having its outer end communicating with the die cavities. The injecting cylinder is in the form of an elongated open ended tube.

A plunger 32 is supported for sliding movement within the tubular injecting cylinder 22. A rod 34 has one end connected to the plunger and the other end may be attached to any suitable mechanism (not shown) for reciprocatingthe plunger within the injecting cylinder. The injecting cylinder has an intake opening or port 36 through its bottom Wall which is spaced inwardly from the discharge or outer end 37 of the injecting cylinder. A frusto-conical seat 38 extends downwardly from port 36. Molten casting material forced into the die cavities by the plunger 32 is initially introduced into the injecting cylinder through the intake opening. The plunger 32 is reciprocable between an inner position illustrated in Figure l at the inner side of the intake opening and an outer position located outwardly beyond the assures J intake opening and adjacent the outer end of the injecting cylinder.

As seen in Figure l, a container or reservoir 46 is located beneath the intake opening and is adapted to contain a supply of molten casting material The container may be heated by any suitable means (not shown) to maintain the casting material in a molten condition, and such means may, for example, comprise an electric induction furnace.

The mechanism for supplying molten casting material from the reservoir to the injecting cylinder will now be described. This mechanism comprises a support 44 which is supported on and secured to the laterally spaced tie bars 46. The outer ends of the tie bars are carried by the platen 1t and the inner ends may be supported by any suitable structure (not shown). The support $4 is formed with a recess 48 in the underside having a groove 56 in the base of the recess for clearing the inje'cting cylinder and other mechanism about to be described.

A displacement device or pumping assembly 52. is provided for delivering molten casting material from the reservoir to the intake opening 36 of the injecting cylinder. The pumping assembly 52 extends into the reservoir and beneath the level of casting material therein. The pumping assembly includes a generally vertically disposed supply tube in the form of a cylinder 54 and a piston 56 which extends into the open lower end of the cylinder and has a cylindrical outer surface which has a close sliding lit with the inner cylindrical surface of the cylinder. The cylinder 54 is provided with a pair of ears 53 which are rigid with the cylinder and extend laterally outwardly from the upper end portion thereof in diametrically opposed relation. The cylinder may be raised and lowered toward and away from the operative position illustrated in Figures 13. In the raised position shown, the upper end portion or nozzle 6% of the cylinder engages the frusto-conical seat 38 surrounding the intake port 36 of the injection cylinder. The nozzle 6% has a vertically extending passage 62 which communicates with the chamber 64 within cylinder 54 and extends upwardly therefrom and is open at the upper end of the nozzle portion 60.

Connected to the ears 58 are upwardly extending rods 66 which are vertically slidable in passages in support 44%. The cars 58 are each formed with a recess 68 extending inwardly from the radially outer extremity thereof between the upper and lower ends, and the portion of. the ear above the recess is formed with a radially inwardly extending slot '79 which extends from the recess 68 to the upper end of the ear and has a width substantially equal to or slightly greater than the diameter or" the rods 66. The rods 66 may thus be assembled with the ears 5% by sliding them laterally inwardiy into the slots '79, the enlargements '72 at the lower ends of the rods preventing the rods from being withdrawn vertically from the slots.

A plate 74 has its opposite ends slidably received on the upper end portions of rods 66. Coil springs 76 surround the upper end portions of the rods above the plate and are compressed between the plate 7'4 and the axially adjustable abutments 78 onthe upper ends of the rods. The coil springs press the plate 74- downwardly against abutments 84? secured to the rods below the plate. 7

The support has a vertical passage 82 for loosely receiving and guiding the lower end portion of a rack 34 secured to and depending from the mid-portion of plate 74. A cylindrical member 66 is supported for retation within a lateral opening in the support 4- 3 which communicates with the passage 62. The cylindrical member 86 has teeth formed about its periphery in the region of the rack and such teeth provide an integral pinion as which meshes with the reel; to raise and lower the latter, and hence, the cylinder'dupon rotation of 4 the cylindrical member 86. The cylindrical member has a polygonal head 90 exteriorly of the support 44 for cooperation with a suitable wrench to rotate the member.

The cylindrical member 86 is also formed with a series of teeth about its periphery which provide a second integral pinion 92. A spring pressed detent 94 cooperates with the teeth of pinion 92 to hold the member 86 in selected positions of rotary adjustment. Specifically, the detent 94 is slidable within a tubular socket member 1% secured in a suitable opening in the support 3 1-. The socket member 96 is cup-shaped and has a coil spring 98 therein compressed between the bottom of the cup member and the enlarged head of the detent 4. The spring surrounds the reduced shank 100 of the det-nt and an enlarged head 102 is secured to the outer end of the shank, the shank slidably projecting through an opening in the bottom wall of the cup. The deteut may be retracted by the head 162 but is normally held in the position shown by the spring 538. The springs 76 on the rods 66 which carry the cylinder provide a resilient cushion to insure that the supply tube or cylinder 5 is not drawn up against the seat 38 of the injection cylinder with excessive pressure. The cylinder 5 will be held in the upper operative position shown during the operation of the machine.

The piston 56 is reciprocated from a lower retracted position shown in solid lines in Figure 3 in which its upper end is beneath the inlet ports in the cylinder to an upper advanced position in which the upper end of the piston assumes the dotted line position shown in Figure 3. The ports 'llltl are arranged in circumferentially spaced relation in a common plane perpendicular to the cylinder axis. The piston is secured at its lower end to a block '112 and extending upwardly from the block through suitable openingsin the support 44 are the spaced rods 114, the upper ends of which are secured to a plate 116. A hydraulic cylinder 118 is provided for raising and lowering piston 56. The cylinder 118 is carried on a frame member 120 which is supported on support 44 by the upright posts 122. The piston (not shown) within cylinder 118 is connected to the plate 116 by a connecting rod 126 which extends through a suitable opening in the frame member 120. The cylinder 118 is of the double-acting type, and hydraulic fluid may be supplied to opposite ends of the cylinder by way of

conduits

128 and 130 to raise and lower the piston therein. An adjusting screw 132 is provided at the upper end of the cylinder 118, the shank of the screw extending into the cylinder and providing an axially adjustable abutment for the piston to vary the upward limit of travel of the piston.

' The cylinder 54 is shown in its operative position in Figures 1-3 in which the nozzle is engaged with the intake port of the injecting cylinder. The cylinder 54 is immersed in the casting material, the normal level of the casting material being indicated by the dotted line 134. The normal level of the casting material thus extends across the cylinder in the region of the fluid passage 62 therein which is of relatively small cross section as compared with the cross section of the interior of cylinder 54. When the piston 56 is in the lower or retracted position illustrated, molten casting material is permitted to enter the chamber 64 through intake ports 110 and to fill the chamber 64 and the passage 62 to the level of casting material in the reservoir. When the piston 56 is raised to its upper or advanced position, the casting material in the chamber 64 is pumped through passage 62 and into the injecting cylinder. Thereafter, the plunger 32 is moved in an outward direction from the retracted I position shown toward the die to force the casting material thus pumped into the injecting cylinder into the die cavities under pressure. If the proper amount of cast ing material has been introduced into the injecting cylinder by the pumping assembly 52, there will be enough casting material to completely fill the die cavities and to leave a relatively small biscuit at the outer endof the injecting cylinder contiguous with the material in the die cavities and against which the plunger 32 maintains a constant pressure until retracted. The limit of upward movement of piston 56 is determined by the setting of adjusting screw 132 so that on one upward stroke of the piston the proper amount of casting material will be delivered to the injecting cylinder. The die will be opened and the plunger retracted after a time interval predetermined to allow the casting material in the die cavities to solidify and to allow the biscuit remaining in the injecting cylinder to form a hardened outer surface suificiently strong to contain the molten interior when the pressure on the biscuit is relieved by opening of the die ahd retraction of the plunger. The piston 56 may be retracted at any time after the plunger 32 has moved outwardly beyond intake port 36. The .cycle described may be repeated over and over, the piston being raised in each cycle prior to the advance of the plunger 32, and then lowered to again fill the pumping assembly.

Should the level of casting material drop to a point such as indicated by the line 140, the reduction in casting material supplied to the injecting cylinder by the pumping assembly 52 in succeeding cycles will be reduced only by the volume of the passage 62 between the

lines

134 and 140. This volume is very small, as compared with the total displacement of the pumping assembly, so that the reduction in volume of the casting material supplied to the injecting cylinder will not be significant. It will be apparent that if the supply passage 62 had substantially the same diameter as the chamber 64 within the cylinder, any change in level of the casting material in the reservoir would produce a much greater change in the volume of casting material displaced.

It is, of course, possible that the level of casting material in the reservoir may drop still further to the level indicated by the line 142, for example. In order to compensate for a drop in level tothe line 142, the cylinder 54 is formed with an integral depending tubular part 146 which is centrally located and which extends into the chamber 64 of the cylinder and forms a continuation of'the passage 62. The piston is formed at its upper end with a central cup-shaped recess 148 to receive the depending part 146 in the upper or advanced position of the piston. By thus providing the part 146 as an extension of the passage 62, the eifect of changes in level of the casting material in the reservoir into the region of the chamber 64 in regard to change in the amount of casting material pumped to the injecting cylinder is minimized.

It will be appreciated, of course, that the intake ports 110, which are open in the retracted position of the piston 56, are closed by the piston upon initial upward movement of the piston toward its advanced position. Should the level of the casting material rise above the normal level indicated at 134, again the effect on the amount of casting material displaced by the pumping assembly 52 will not be significant, as will be apparent.

Figure 6 illustrates a modification. The vertically disposed supply tube .150 is provided with ears 152 to which the'lower ends of rods 154 are connected in any suitable manner. The upper ends of the rods may be connected to and operated by mechanism similar to that employed for the rods 66 in the previous embodiment. The supply tube may be raised and lowered toward and away from the operative position illustrated in which its nozzle end portion 156 seats against the frusto-conical seat 38 surrounding the intake opening 36 of the injecting cylinder 22. The supply tube has, an elongated vertical through passage 158 of relatively small diameter.

A cylinder 160 is provided having an inside cylindrical surface of a diameter approximating the outer cylindrical surface of the supply tube to provide a sliding fit. Thus, the supply tube and cylinder 160 together provide a 6 the piston of the assembly. The lower end of the cylinder is carried by a block 164, and rods 166 are secured to and extend upward from the block 164. The upper ends of the rods 166 may be associated with and operated by mechanism similar to the mechanism for the rods 114 of the first embodiment.

The cylinder 160 is reciprocable between a lower retracted position shown in solid lines and an upper advanced position indicated in dotted lines. In the lower position illustrated, casting material from the reservoir is permitted to enter the chamber 168, defined by the interior of the cylinder 160 and the lower end of the supply tube, through ports 167 and to fill the chamber 168 and the passage 158 to the level of casting material in the reservoir. Upon initial upward movement of the piston, the ports 167 are closed.

The cross sectional area of the passage 158 is substantially smaller than the cross section of the chamber 168 so that upon changes in the level of the casting material, from the normal level indicated at 170 to a lower or higher level along the passage 158, the change in volume of the casting material admitted through the ports 167 prior to an upward stroke of the cylinder 160 is relatively small compared to the displacement of the assembly 162.

What I claim as my invention is:

1. In die casting structure including a reservoir for molten casting material and apparatus located above the level of casting material in the reservoir for injecting casting material from the reservoir into a die, means for supplying casting material from the reservoir to the injecting apparatus including a pumping assembly extending into the reservoir and beneath the level of casting material therein, said pumping assembly including a cylinder member, a piston member within said cylinder member and defining therewith a pumping chamber, said piston and cylinder members being relatively reciprocable between first and second positions to increase and decrease respectively the volume of said pumping chamher, a fluid passage means communicating with. said chamber at one end of said cylinder member and extending upwardly above the level of casting material in the reservoir for communication with the injection appara tus, means for admitting casting material from the reservoir into said chamber when said piston and cylinder members are in the first position aforesaid to fill said chamber and passage means to the level of casting material in the reservoir whereby the castingmaterial so admitted may be pumped to the injection apparatus through said passage means upon relative movement of said members from the first to the second position thereof, said passage means being of substantially smallercross section than said pumping chamber whereby changes in the level of casting material in the reservoir along said passage means will not materially aflEect the volume of casting material pumped to the injecting apparatus by said pumping assembly, a tubular part extending into said chamber from said one end of said cylinder member providing an extension of said passage means of substantally smaller cross section than said chamber, and said piston member having a recess for receiving said tubular part in the second position of said members.

2. In die casting structure including a reservoir for molten casting material -and apparatus located above the level of casting material in the reservoir for injecting casting material from the reservoir into a die, means for supplying casting material from the reservoir to the injecting apparatus including a pumping assembly extending into the reservoir and beneath the level of casting material therein, said pumping assembly including a generally vertical cylinder, a piston within said cylinder and defining therewith a pumping chamber, said piston being reciprocable in a generally vertical direction within said cylinder between a lower retracted position and a raised pumping assembly 162, the supply tube 150 constituting 75 advanced position to increase and decrease respectively the volume-of said pumping .chamben-means-holding saidcylinder-infixed positionadjacent the injection apparatus, a fiuid passage means communicating withsaid chamber at theupper end of said cylinder and extending upwardly above the level of casting material in the reservoir for communication-with'theinjection apparatus, mea'ns'for admitting casting material from the reservoir into saidchamber when said pistonis in retracted posi tion to fillsaid chamber and passage means 'to the level of casting material inthe reservoir'whereby the casting material so admitted'may be pumped to the injecting apparatus through said passage means upon movement of -said piston from its retracted to its advancedposition, said passage being of substantially smaller cross section than said cylinder whereby changes in the level of casting material in the reservoir along said passage means will not materially atiect the volume of casting materialpumped-to the injecting'apparatus by-said pumping assembly, said'admitting means including a port in said-cylinder open in the retracted position ofsaid piston and closed by said piston when the lattermoves initially from retracted position toward advanced position, said cylinder having a generally =vertical tubular partextend ing axially of said-cylinder from said upper end thereof and downwardly into said chamber to provide an extension of said passage means of substantially smaller cross section than said cylinder, said tubular part defining with said cylinder-an annular space therebetween, and said piston having a generally'central recess in its upper end for closely receiving said tubular part substantially. in its entirety in the advanced position of said piston.

3. Die casting structure as defined in claim 2 in which the upper end of said piston, in the advanced position of the latter, is disposed closely adjacent to the upper end of said cylinder to reduce the volume of said pumping chamber to a minimum in the advanced position of said piston.

4. In die casting structure, means for supplying molten casting material from a reservoir to a point of use including a fluid displacement device extending into the reservoir and beneath the level of casting material therein, said device including a cylinder member, a piston member within said cylinder member and defining therewith a pumping chamber, said piston and cylinder members being relatively reciprocable between first and second positions to increase and decrease respectively the volume of said pumping chamber, a fluid passage means communicating with said chamber atone end of one of said members and extending upwardly above the level of casting material-in the. reservoir, means for admitting casting material from the'reservoir into said chamber whens'aid piston and cylinder members are in the first position aforesaid'to fill said chamber and passage means to the levelof casting material in=-the reservoir whereby the casting material so admitted may be pumped up- Wardly through. said passage 'means upon relative movement of said members from the first to the second position thereofisaid passage means being of substantially smaller cross section than said pumping chamber whereby changes in the level of casting material in the reservoir along said passage means will not materially alfect the volume :of casting material pumped upwardly through said passage-'means by said device,- =a tubular partextending 'into said chamber from said one end of said one member providing' an extension of-said passage-means of substantially-smaller erosssectionthansaid chamber, and the other of saidmembers having a recess for receiving said tubular part in: the second position of said members.

'5. 1m die ea'sting structure, mea-ns 'forsupplying molten cast-ing material from a reservoir to a point of use inc"5 ing =a fluid displacement device extending into the reservoirand beneath the level of casting material therein, said device including a vertical-cylinder, a piston within said cylinder and defining-therewith a pumping chamber, said piston-being reeiprocable in agenerally vertical direction within said cylinder between a lower retractedposition and a raised advanced position to increase and decrease respectively the volume of 'said pumping chamber, 'afiuid passage means communicating --with said chamber at the-upper end-of said cylinder and-extending upwardly above the level "of casting material in the reservoir; means for admitting casting material from the reservoir-intosaid chamber when said pistonisin'retracted position to fillsaid chamber and passage-means to the level of casting material-in the reservoir whereby the casting material so admitted may be pumped upwardly through'said passage means upon movement of said piston-from its retracted to its advanced position, said passage means being of substantially smaller cross section than saidcylinderwhereby' changes in the level of casting material-in-the reservoir along said'passage means Wil not materially affect-thevolume-of-casting material pumped upwardly throughsaid passage-means by said device, said admitting means including a port in said cylinder open'in .the retracted position of said piston and closed by said-piston when the latter moves initially from retracted position toward advanced position, said cylinder having a generally vertical tubular part extending axially of said cylinder from said upper end thereof and downwardly into said chamber to provide an extension of said passagemeans of. substantially smaller cross section than said cylinder, said tubular part defining with said cylinder an annular space therebetwcen, and said piston having a generally central recess in its upper end for closely receiving said tubular part substantially in its entirety in theadvanced position of said piston.

References Cited in the file of this patent UNITED STATES PATENTS 533,685 Underwood Feb. 5, 1895 703,420 Hunter July 1, 1902 1,279,249 Bungay Sept. 17, 1918 1,534,492 Bechman Apr. 21, 1925 1,664,296 Hamerstadt Mar. 27, 1928 1,944,199 Tischler Jan. 23, 1934 2,120,333 Kubo June 14, 1938 2,582,029 Halward Jan. 8, 1952 2,582,137 Kux Jan. 8, 1952 2,655,699 Morin Oct. 20, 1953 2,786,247 Stern Man-26, 1957