US2837793A - Die casting machine - Google Patents

Description

June 10, 1958 Filed Dec. 27. I955 L. RING DIE CASTING MACHINE 3 Sheets-Sheet 2 June 10, 1958 RING 2,837 ,793

DIE CASTING MACHINE? 5 Sheets-Sheet 3 Filed Dec. 27. 1955 N FIG.5.

uvmvroa LUOIAN RING ATTORNEYS United States Patent O DIE CASTING MACHINE Lucian Ring, Clawson, Micln, assignor, by mesne assignments, to Ring Aluminum Development Company,

Clawson,'Mich., a corporation of Michigan Application December 27, 1955, Serial No. 555,372

4 Claims. (Cl. 22-68) 1 This invention relates to die casting and refers more particularly to a die casting machine. t Die casting machines of the type involved herein include an injection cylinder sometimes called a cold chamber having a plunger therein for filling a die cavity with molten casting material upon advance of the plunger in the cylinder. Before each advance of the plunger, it is necessary to introduce into the cold chamber a charge of molten casting material.

With the above in view,*one object of this invention is -to provideimproved mechanism for introducing a charge of molten casting material into the cold chamber. Another object of this invention is to provide a die casting machine which is substantially foolproof in operation and in which the advance of the plunger to' fill the die cavity is timed withrespect to the introduction of'molten casting rnaterial'into the cold chamber so as to provide the most efiicient operation possible.

, Still another object of the invention is to provide a supply tube for delivering molten casting material from a reservoir to the cold chamber having means for moving the supply tubetoward and away from a position in which; its discharge end communicates with an intake opening in the: cold chamber. In this connection, it is also an object-of the invention to provide resilient means for-limiting the pressure of the engagement between the discharge end of the supply-tube and the seat surrounding the intake opening of the cold chamber.

A further object of the invent1on 15 to provlde an arrangement whereby the solidification of molten casting material in and about the supply tube at its discharge end is avoided. In the absence of the arrangement provided for this purpose, the cold chamber is apt to with-.

draw heat from the molten casting material at the discharge end thereof. so that solidification occurs.

' Other objects of theinventionwill become apparent as the following description proceeds especially when taken. in conjunction with the accompanying drawings,

wherein: I

Figure 1 is a side elevation view, partly in section, of a die casting machine constructed in accordance with thev present invention; 5 I e Figure '2 is a view taken along the line 2-2 on Figure e Figure 3 is a fragmentary top plan view of the machine,

Figure 4is anenlargedsectina1 view of the discharge end of the supply tube in association with the cold chamber' at the intake port.

Figure 5 is a diagrammatic view of the machine showing the electrical and hydraulic controls for the operation of the machine.-, v

;.Figure 6 is a wiring diagram.

Figure 7 is an enlarged detail of a portion of Figure 1. a Figure 8 is a sectional view taken along the line 8-8 on Figure 4.

eferringnow moreparticularly to the drawings, the machine comprises a stationary support or platen 10 having a stationary die part 12 secured thereto. A movable the closed position of the die and are formed with regis tering recesses to define the die cavities 24.

Molten casting material which may, for example, be

of the lightweighttnonferrous type, such as aluminum or magnesium, is introduced into the die cavity by an injection cylinder or cold chamber 26. The cold chamber 26 is secured in platen 10 and projects therebeyond through fixed die part 12 having its outer end communicating with the die cavity. The cold chamber is in the form of an elongated open ended tube which is formed with a plurality of elongated passages 28 which extend from the inner end thereot to a point adjacent the outer end (see Fig. 3). These passages 28 are not connected and terminate short of the outer end of the cold chamber and have tubes 30 extending thereinto connected to inlet pipes 32. The tubes 30 terminate short of the outer closed ends of the passages and are of substantially less diameter than the passages to provide a turn for cooling medium such as water introduced into tube 30 by pipe 32. The coolant is withdrawn through discharge pipes 34. By this means, the cold chamber 26 is maintained at a uniform relatively cool temperature. A plunger 36 is supported for sliding movement within the tubular cold chamber 26. Plunger 36 is reciprocated within the cold chamber by a shot cylinder 38 which is carried by the support 40. Tie rods 42 connect the stationary platen 10 and the support 40. The shot cylinder 38 has a piston 46 therein. from the piston 46' and is connected to a rod 50 by a coupling 52. The rod 50 has its outer end connected to-plunger 36 so that reciprocation of the piston 46 within the shot cylinder eiiects a corresponding reciprocation of the plunger 36 in the cold chamber. The support 40 is formed with a suitable opening for slidably receiving the connecting rod 48.

The cold chamber has an intake opening or port 54 through its wall which is spaced inwardly from the discharge opening 56 at the outer end thereof axially of the cold chamber. Molten casting material forced into the die cavity by plunger 36 is initially introduced into the cold chamber through the intake opening. The plunger 36 is reciprocable between an inner position illustrated in Fig. l at the inner side of the intake opening, and an outer position located outwardly beyond the intake opening. 7

i The mechanism for initially charging the cold chamber will now be described. This mechanism comprises a support 58 which is supported on and secured to the tie bars 42. As seen in Fig. 2, the tie bars 42 extend through the support 58 at laterally spaced points. The support 58 is formed with a recess 60 in the underside having groove 62 in the base of the recess for clearing the coldcharnber and other mechanism about to be described. T As seen in Fig. l, 'a'container or reservoir 64 is located beneath tie bars 42 and between the stationary platen 10' and the shot cylinder support 40, this reservoir containing a supply of molten casting material, the top surface of which is indicated by the line 66. The container may be heated by any suitable means to maintain the casting material in a molten 'conditiom A supply tube is provided for delivering molten casting material from the reservoir to the intake opening 54 of the cold chamber which is located directly above the casting material inthe reservoir. The supply tube is A connecting rod 48 extends indicated generally at 68 and includes a tubular cylinder 70 below the level of casting material in the reservoir which is open at the lower end and which is closed by a transverse wall 72 at the upper end. The upper end of the cylinder 70 is secured to the yoke 74 in any suitable manner. The-supply tube also includes an upper end or'nozzle 76 which is likewise secured to the yoke 74. ln de-tail, the nozzle 76 has a reduced lower end 78 which is secured in a passage through the base of the yoke 74. The nozzle has a through passage 82 which'comm'unicates with the interior of cylinder 70 by a passage inthe transverse wall 72 of the cylinder.

A tubular discharge member 86 is secured in the upper end of-the-nozzle 76, the discharge member being open ended andproviding a continuation of the passage 82 through the nozzle. The supply tube 68 which includes the cylinder 70 and the nozzle 76 and discharge member 86 may be raised and lowered toward and away from the operative position illustrated in Figures 1, 2 and 4. As seen particularly in Figure 4, the upper end of the dischargemember 86 is frusto-conical as indicated at 90, and located in angularly spaced relation 90 apart around this surface 90 are the projections 92 which may be integral with the discharge member 86. These projections 92 engage the frusto-conical seat 94 which surrounds the intake opening 54 of the cold chamber. The projections 92 not only serve as pilots for guiding and properly locating the supply tube in operative relation to the intake opening, but also serve to maintain the major portion of the upper end of the discharge member 86 in spaced relation with the cold chamber.

The purpose of this is to prevent the upper end of the supply tube 68 from becoming excessively cool through contact with the cold chamber. Excessive cooling of the upper end of the supply tube may result in solidification of the casting material in the upper end of the supply tube. The projections 92 also provide spaces 95 for the return of excess casting material from the intake opening of the cold chamber to the reservoir.

Secured to each leg of the yoke 74 is an upwardly extending rod 96. These rods are slidably received in suitable openings in the support 58. A plate has its opposite ends slidably received on the upper ends of the rods. Coil springs 102 surround the upper end portions above the plate and are compressed between axially adw justable abutments 104 and plate 100. The coil springs press the plate 100 downwardly against abutments 108 secured to the rods below the'plate.

The support 58 has a vertical passage 110 for loosely receiving and guiding. the lower end portion of a rack 112 secured to and depending from the mid portion of plate 100. A cylindrical member 114 is supported for rotation within .a lateral opening in the support 58 which communicates with the opening 110. The cylindrical member 114- has teeth formed about its periphery in the region of the rack and such teeth provide an integral pinion 116 which meshes with the rack to raise and lower the rack and, hence, the supply tube upon rotation of the cylindrical member. The cylindrical member 114 has a polygonal head 117 exteriorly of the support 58 for cooperation with a suitable wrench to rotate the member.

The. cylindrical member 114 is also formed with a' series of teeth about its periphery which provide a second integral pinion 118. A spring pressed detent cooperates with the'teeth of pinion 118 to hold the member 114' in selected positions of rotary adjustment. Specifically, the detent 120 is slidable within a tubular socket member 122. secured in a suitable opening in the, support 58. The socket. member 122 is cup-shaped and has a coil spring 124 therein compressed between the bottom of the cup member and the enlarged head of the detent 120. The spring surrounds the reduced shank 128 of the detent, and an enlarged head 130 is secured to the outer end of the shank, the shank slidably projecting through and opening in the bottom wall of the cup. The detent may be retracted by the head 130. but is normally held in the position shown by the spring 124. The springs H12 on the rods 96 which carry the supply tube provide a resilient cushion to insure that the supply tube is not drawn up against the seat 94 of the cold chamber with excessive pressure. In this way, the supply tube and the engaging projections 92 thereon are protected against damage.

A piston 132 slidably extends into the lower open end of the cylinder '70 and is reciprocated from a lower position in which its upper end is beneath the inlet ports 134 in the cylinder to a position in which the upper end of the piston extends above the ports to force molten casting material from the cylinder into the cold chamber through the intake opening 54. Ports 134 are, of course, below the level of the casting material in the upper position of the supply tube. The piston is secured at its lower end to a block 136and extending upwardly from the block through suitable openings in the support 58 are the spaced rods 138-the upper ends of which are secured to a plate 140. A hydraulic cylinder 142 is provided for raising and lowering piston 132. The cylinder 142. is carried upon a frame member 144 which is supported on support 58 by the upright frame members 146. The piston 148 within the cylinder 142 is connected to the plate 148 by a connecting rod 150 which extends through a suitable opening in the frame member 144.

The operation of the apparatus can best be understood by referring to Figures 5 and 6 showing the hydraulic and electrical circuits for controlling the cycle of operation. Before a cycle of operation is initiated, the movable die part 14 is spaced to the left of the position shown in Figuresl and 5 so that the die is open and a previously cast article may be removed from the cavity. The cylinder assembly 16 for moving the movable die part 14 has the hydraulic fluid lines 156 and 158 for alternately admitting and discharging hydraulic fluid from opposite ends of the cylinder as determined by the solenoid controlled 4-way 2-position valve 160. The solenoid controlled valve 162 is also a 4-way 2-position valve and controls the flow of hydraulic fluid to and from the opposite ends of the cylinder 142 by way of hydraulic lines 164 and 166.

It will be noted in Figure 5 that the stroke of the piston 148 in cylinder 142 is variably determined'by the adjustment of the abutment 168 which is in the form of a screw threaded into the upper endof the cylinder for axial adjustment. In this manner, the height to which the piston 132 can be raised is varied to vary'the amount of casting material introduced into the cold chamber.

The solenoid controlled valve 170 is a 4-way 2-position valve and controls the flow of hydraulic fluid to and from the opposite ends of the shot cylinder 38 by way of the hydraulic lines 172 and 174. Prior to the initiation of a cycle, the solenoid 160' for the valve 160 is de-energized and the valve assumes its normal position by means of .a spring not shown for admitting hydraulic fluid under pressure to the cylinder 16 through line 158 and for exhausting fluid from the opposite end of the cylinder through line 156 to open the die. The solenoid 162 is likewise deenergized and the corresponding valve assumes'its normal position admitting fluid under pressure to line 164 and exhausting fluid from line 166 to lower the piston 132 beneath the intake openings134 in the supply tube. Solenoid 170' is also de-energized so that valve 170 can assume its normal position by spring pressure to admit hydraulic fluid under pressure to line 172 and exhaust line 174 to retract the plunger 36 in the cold chamber.

In order to initiate a cycle of operation, the manual start button 176 is closed to energize solenoid 160' through circuit 177 which is connected across lines L1 and L2." Relay R is also energized to close the normally open contact r of the holding circuit. 178 to. maintain the solenoid 160' energized, afterrelease of the normally. open start button. Energization of the solenoid 160,

"limit switch LS3.

shifts valve 160 to admit fluid under pressure through line 156 and exhaust line 158 to move die'part 14 against die part 12 to close the caviiy 24. As the die part 14 reaches closed position, an abutment 180 .on carrier 15 engages and closes limit switch LS1 and holds the same closed. As a result, solenoid 162' is energized through circuit 181 to shift valve 162 to a position wherein fluid under pressure is admitted to line 166 and exhausted from line 164 to raise piston 132 and so force into the cold chamber through the intake opening 54 a predetermined quantity of molten casting material. The quantity thus delivered is determined by the setting of the adjustable abutment 168. As piston 132 reaches its upper limit, an abutment 180 engages and closes limit switch LS3. If necessary, the position of limit switch LS3 may be varied for operation by abutment 180 at the upper limit of piston 132 as required by the setting of adjustable abutment 168. As a result, solenoid 170' is energized through circuit 183 shifting valve 170 to a position wherein fluid under pressure is delivered through line 174 and exhausted from line 172 to cause the plunger 36 to advance from the position shown at the inner side of the intake opening 54 outwardly beyond the intake opening to force the charge of casting material previously introduced to the cold chamber into die cavity 24.

, .The time delay relay TRl is associated with solenoid 162' and determines the period of time that this solenoid is'energized. When the coil 182 of this time delay relay is sufficiently heated by the current passing through it through line 184, the contact 186 thereof swings toward the/coil to break circuit with line 188 and thereby 'deenergize solenoid 162. As a result, valve 162 moves to its normal position to retract or lower piston 132 to its initial starting position. This, however, does not take place until the plunger 36 has advanced outwardly past the intake opening 54 in the cold chamber. 7

It is desirable to maintain the plunger 36 in its outer or advanced position in the cold chamber to maintain the casting material in the die cavity under pressure during solidification. The period of time that the plunger is thus held in its outer position is determined by a time delay relay TR2. The coil 190 of this relay is energized by line 192 at the same instant that solenoid 170 is energized. Since the limit switch LS3 will be opened upon retraction of piston 132, a relay RR is provided having a contact rr in a holding circuit 194 across the limit switch LS3 which is normally open but closes upon energization of the relay. After a predetermined interval of time, the contact 196 of the time delay relay TR2 opens breaking the circuit to the solenoid 170 and thereby permitting retraction of the plunger 36 to its initial or starting position.

A time delay relay TR3 is provided for retracting the movable die part 14. The time delay relay TR3 is in a circuit 198 which also includes a relay RRR having a normally open contact rrr in a holding circuit 200 bridging the limit switch LS3 to maintain the circuit 198 closed after the piston 132 is retracted to open limit switch LS3. The time delay relay TR3 has a coil 202 which, after the lapse of a predetermined period of time, causes contact 203 to make contact with the line 206 thereby energizing the relay RRRR to open the normally closed contact rrrr. As a result, the solenoid 160' is de-energized to enable the retraction of the movable die part. The contact rrrr' moves as a unit with the contact rrrr to open the circuit 198. The time delay relays TR2 and TR3 are energized at the same time by the closing of The time interval set into TR3 is slightly less than that of TR2 so that the movable die part 14 first moves to open position after a time interval determined to permit solidification. At the time the die opens, the plunger 36 is still urged outwardly and ejects any casting material remaining in the cold chamber through the fixed die 12. Shortly after the die part 14 opens, time delay relay, TR3 operates to retract the plunger. i I Briefly, the'sequence of operation is (1) the movable die part 14 is advanced to closed position,"(2) the piston 132 is'raised to deliver to charge of casting materialto the cold chamber, (3) plunger 36 advances to force the casting material into the die cavity, (4) the piston 132 retracts after a time interval determined to allow the ad vance' of plunger 36 past the intake port 54, (5) the die is opened after a time determined to allow. the, article to solidify and the article cast therein is removed, and (6) after the die opens for removal of the article the plunger retracts. j

The 'next cycle of operation 'is initiated in the same way by depressing the manual start button. l The spaces for the return of excess casting material do not materially reduce the amount of material introduced to the cold chamber, sincetthe timing is such that the plunger 36 promptly advances to move the casting material outwardly beyond the intakeopening 54.

What I claim as my invention is: 1. Die casting apparatus comprising a die having a cavity, means for injecting molten casting material into said cavity including'a cylinder having a discharge opening communicating with said cavity and having an intake port in the underside spaced from said discharge opening axially of said cylinder, means for cooling said cylinder, said cylinder having an annular seating portion surrounding said intake port, means for introducing molten casting material into said cylinder including a reservoir for molten casting material beneath said cylinder, an upright supply tube having its lower end immersed in the molten casting material in said reservoir and movable vertically toward and away from an upper operative position in which the upper end portion of said tube communicates with said intake port, angularly spaced pilot projections on said upper end portion of said supply tube engageable with said seating portion in the operative position of said supply tube to guide said upper end portion into proper seating relationship with said seating portion and also to maintain a major part of said upper end portion out of contact with said seating portion, thereby minimizing heat transfer from said cylinder to said supply tube, said projections defining angularly spaced relatively restricted passages between said upper end portion of said supply tube and said seating portion for the return of excess casting material along the exterior of said supply tube to said reservoir, thereby further minimizing heat transfer from said cylinder to said suppy tube.

2. Die casting apparatus comprising a die having a cavity, means for injecting molten casting material into said cavity including a cylinder having a discharge opening communicating with said cavity and having an intake port in the underside spaced from said discharge opening, means for cooling said cylinder, said cylinder having an annular seating portion surrounding said intake port, means for introducing molten casting material into said cylinder including a reservoir for molten casting material beneath said cylinder, an upright supply tube communicating with the molten casting material and said reservoir and movable toward and away from an operative position in which the upper end portion of said tube communicates with said intake port, angularly spaced pilot projections on one of said portions engageable with the other of said portions in the operative position of said supply tube to guide said upper end portion into proper seating relationship with said seating portion and also to maintain a major part of said upper end portion out of contact with said seating portion, thereby minimizing heat transfer from said cylinder to said supply tube, said projections defining angularly spaced relatively restricted passages between said portions for the return of excess casting material along the exterior of said supply tube, thereby further minimizing heat transfer from said cylinder to said supply tube.

3. Diec'asting apparatus comprising a cylinder having a discharge port and having an intake opening in the under sidespaced from said discharge port, said cylinder having'a seating portion surrounding said intake opening, means for cooling said cylinder, means for introducing molten, casting material into said cylinder including a reservoir formolten v casting material beneath said cylindei', an upright supply tube communicating with the molten casting material in said reservoir and having the upper end portion communicating with said intake opening, angularly spaced pilot projections on one of said portions engageable with the other of said portions to maintain a substantial part of said upper end portion of said supply tube out of contact with said seating portion of said cylinder, thereby minimizing heat transfer from said cylinder to said supply tube, said projections defining angularly spaced relatively restricted passages between said portions for the return of excess casting material to said reservoir along the exterior of said supply tube, thereby further minimizing heat transfer from said cylin der to said supply tube.

4. Die casting apparatus comprising a cylinder having a discharge port and having an intake opening spaced from said' discharge port, said cylinder having a seating portion surrounding said intake opening, means for introducing molten casting material into said cylinder including a reservoir for molten casting material beneath said cylinder, a supply tube communicating with the molten casting material in said reservoir and having an end portion communicating with said intake opening, angularly spaced pilot projections on one of said portions engageable with'the other of said portions to maintain a substantial part of said end portion of said supply tube out of contact with said seating portion of said cylinder, thereby minimizing heat transfer from said cylinder to said supply tube, said projections defining angularly spaced relatively restricted passages between said'portions for the return of excess casting material to said reservoir.

References Cited in the file of this patent UNITED STATES PATENTS 810,832 Wicks Jan. 23, 1906 1,226,408 Tenca May 15, 1917 1,961,942 Pack June 5, 1934 2,137,764 Wagner Nov. 22, 1938 2,143,323 Korsmo Jan. 10, 1939 2,145,956 Stern Feb. 7, 1939 2,195,360 Daescn Mar. 26, 1940 2,206,211 Wagner July 2, 1940 2,243,293 Stahl May 27, 1941 2,244,816 Von Lynn June 10, 1941 2,456,423 Jobst Dec. 14, 1948 2,465,580 Ernst Mar. 29, 1949 2,519,739 Butner Aug. 22, 1950. 2,565,522 Renier Aug. 28, 1951 2,582,137 Kux Jan. 8, 1952 2,620,528 De Sternberg Dec. 9, 1952 FOREIGN PATENTS 513,992 Canada June 21, 1955 883,056 France Mar. 15, 1943 OTHER REFERENCES Ser. No. 127,067, Wagner (A. P. C.), published June 1, 1943.

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