US3698471A

US3698471A - Automatically operated multiple cavity die for low-pressure chill-casting

Info

Publication number: US3698471A
Application number: US75920A
Authority: US
Inventors: Pierre Chatourel; Jean Lefebvre
Original assignee: Renault SAS
Current assignee: Renault SAS; Regie Nationale des Usines Renault
Priority date: 1969-10-15
Filing date: 1970-09-28
Publication date: 1972-10-17
Anticipated expiration: 1989-10-17
Also published as: ES383980A1; DE2050750C3; DE2050750B2; FR2063426A5; DE2050750A1; SU441695A3; SU421169A3; JPS4817415B1; GB1322547A

Abstract

This device permits the low-pressure chill-casting of parts such as engine pistons in mold cavities formed in pairs of half-dies, said mold cavities being aligned and formed in a fixed half-die receiving the duct supplying the molten metal thereto and in the movable half-die adapted to move by translation away from said fixed half-die by means of retractable members of the type comprising movable core elements, the automatic control units associated with said half-dies being adapted to assemble and disassemble said core elements through a sequence of mechanical movements produced by an actuator, automatic means being associated with the device for ejecting and discharging the castings.

Description

[151 3,698,471 51 Oct. 17, 1972 United States Patent Chatourel et al.

0 09 X X BMBH 4344 6/66 1411 6 6" 1 l s sh nwwmh 0cm MDPPS [III [54] AUTOMATICALLY OPERATED MULTIPLE CAVITY DIE FOR LOW- PRESSURE CHILL-CASTING [72] Inventors: Pierre Chatourel; Jean Lefebvre, I

both of Billancourt,. France [73] Assignee: Regie Nationale Des Usines Renau, Primary Examiner-R. Spencer Annear Binancoun, France Attorney-Stevens, Davis, Miller & Mosher Sept. 28, 1970 I [2]] Appl. No.: 75,920

[22] Filed:

ABSTRACT 4 y This device permits the low-pressure chill-casting of v parts such as engine pistons in mold cavities formed in pairs of half-dies, said mold cavities being aligned and [30] Forelgn Apphcanon Prmmy Data formed in a fixed half-die receiving the duct supplying Oct. 15, 1969 the molten metal thereto and in the movable half-die France......................6935366 adapted to move by translation away from said fixed [52] U.S. Cl. L................,.164/340, 164/346, 164/113 half-die y means o e ractable members of the type 51 Int. Cl. 33/04 comprising movable core elements, h omatic control units associated with said half-dies being mble said core ele- [58] Field of Search;

adapted to assemble and disasse ments through a sequence of mechanical movements produced by an actuator, automatic means bein sociated with the device for the castings.

References Cited UNlTED STATES PATENTS g asejecting and discharging 2,254,295 9/1941 Kohl et al. .................l64/303 9 Claims, 16 Drawing Figures PATENTEDnm 17 m2 SHEET 2 BF 8 lllll L x PATENTEDucI 11 I972 SHEEI 7 [IF 8 xi M AUTOMATICALLY OPERATED MULTIPLE I CAVITY DIE FOR LOW-PRESSURE CIIILL- I CASTING 1 I The present invention relates to chill-casting devices and hasspecific referenceto a device for the .produc- I tion of castings, notably engine pistons,- by low-pressure jectionable when it is contemplated to produce great numbersof such castings, due to the high cost of labor and/or the insufficient efficiency, since the castings must be made manuallyand separately.

On the other hand, the easy automation and high efticiency of die casting processes are impaired'by the high cost of the initial equipment and the depreciation charges inherent to the machines, not to mention the relatively rapid wearof expensive tools which is increased by the bulkycharacter of the castings such as pistons and also by the fragility of the core-type molding elements utilized for obtaining the internal shape of these pistons. A

It is the essentialobject of the present invention to provide a low-pressure, multiple-cavity chill-casting device, notably for the mass production of engine pistons, which is free of the inconveniences set forth hereinabove. I

The .device according to this invention is characterized essentially in that the molds comprise each two half-dies, i.e., a fixed half-die and a movable half-die, that the mold cavities are aligned in even number and formed on the one hand in a fixed half-die receiving the feed duct and on the other hand in a movable half-die adapted to move by translation away from the fixed die and in the plane joint of these two half-dies, by means of retractable mold elements whether of single or compound type adapted to be assembled by means of core membersknown per se, wherein the core members are fitted in position or removed therefrom by standardized automatic control units each adapted to control two mold cavitiesand of which the core member fitting or release operations are produced through a sequence of mechanical movements known per se under the control of a single actuator, automatic means also known per se being associated with the device for ejecting and discharging the cluster of castings.

It is another object of the present invention to combine these mechanical mold stripping units with the structure of automatic low-pressure casting machines intended for casting miscellaneous parts.

Thus, for example, in the frequent case of engine I pistons not requiring any relief or projection cast integrally therewith on their top faces, these pistons are cast with their top faces coupled and opposed along two Parallel rows of pistons disposed symmetrically on This deviceis adapted to be combined with a lowpressure chill-casting device described and illustrated in the U.S. Pat. Ser. No.-47,978 ofJune 22, 1970.

2 With the present device the" high productionrates hitherto inherent, only todie-casting methods can be obtained, due to the use of multiple mold cavities and also to the automatic control of the casting and molding operations. On the other hand the low pressure to which the injected molten metal is subjected reduces considerably the wear and tear of the tools and equipments, notably the core membersand spindles constituting the piston cavity molding elements. These relatively thin elements surrounded by a relatively sturdy and rigid supports, on which the driving and control means can be mounted without difficulty to constitute a sturdy and precision assembly adapted to withstand continuous operationconditions. Moreover, assembling the detachable mold elements on identical mass-produced control units affords a simpler and more economical construction of the mechanism while increasing its strength.

Furthermore, limiting these units to the control and actuation of two core structures corresponding to the interior of two castings eliminates any risk of wedging due to the thermal expansion of parts during the ope ration, thus ensuring a satisfactory operation of the mechanism under all temperature conditions.

Finally, this device ensures substantial savings in the usually'lost riser, constituting a serious inconvenience in die-casting processes, in comparison with conven tional gravity casting, since the only risers are the casting slot connected to the common molten-metal supply duct. This advantageous feature is further improved in the case of flat-topped pistons cast by pairs in mutual opposition, since the number of castings is doubled for an equivalent weight of sprue or riser metal implemented. In either case, and especially in the last one, the casting slotopens into the thickest zone of the casting, thus ensuring a gradual setting of the metal and improving the quality of the final casting.

in the case of equipment opening along a vertical joint with a retractable lower portion, the fallof the cluster of castings towards the discharge means will complete the completely automatic cycle of operation of the device, thus ensuring an extremely regular production. Under these conditions the operators duty consists simply in supervising and adjusting or regulating the operating conditions.

A preferred form of embodiment of this device will now be described more in detail with reference to the attached drawings illustrating diagrammatically by way of example a piston casting unit, but it will readily occur to those conversant with the art that the invention should not be construed as being strictly limited to this application. in the drawings:

FIG. 1 illustrates an elevational and part-sectional general view of the device of this invention;

FIG. 2 shows a cluster of 4 pistons cast by using the device of FIG. 1;

I FIG. 3 illustrates the device of this invention in the specific case of flat-topped pistons cast in two linear rows of pistons disposed by pairs in a single cluster;

FIG. 4 illustrates in perspective a cluster of eight pistons cast by using the device of FIG. 3;

respectively, and the other in fragmentary sections along the lines VI -VI' and VI VI of FIG. 5;

, FIG, 7 illustrates in fragmentary section details of a three-element core assembling head of a mechanical control unit, the section being taken along the line 7 VII-VII of FIG. 6;

FIG. 8 shows in sectional view details of a three-element core assembling head,.the section being taken along the lineV-V'. of FIG. 6;

FIGS. 9 and 10 showin section constructional and operating details of a five-elementcore assembling head, the section being taken along the lines V-V' and VII-VII of FIG. 6; j

FIGS. 11 and 12 show the same details as FIGS. 8 and 9, respectively, but in the case of larger castings;

FIG. 13 is a sectional view taken along the line V-V' of FIG. 6 showing details of the assembling of the lateral core elements;

FIG. 14 is section taken along the line XIV-XIV of FIG. 13;

FIG. 15 shows in section details of the assembling of the pivot means of the pivotal mounting of core elements, the section being taken along the line'VV of FIG.6,and

Y F IG. 16 is a section taken along the line XVI-XVI of FIG. 15. I

Referring first to FIG. 1,-a low-pressure casting furnace 1 and its injection device 2 according to the above-mentioned patent application are associated with a fixed chill-casting half-die 3 having a plurality of mold cavities 3 this half-die 3 being rigid with a support 4 and a frame structure or floor 5.

Secured to a tray 6 movable on said frame structure 5 is a movable half-die 7 having a plurality of mold cavities 7 symmetric to mold cavities 3,. Mounted to the base of half-die 7 is the mold bottom element 8 receiving the multiple mold cavities 8, adapted to shape the piston crowns or heads, and also heated inbling of core elements 10 adapted in their'assembled condition to constitute the mold core. for shaping the inner cavity of the piston during the casting process.

Mechanisms 11 for inserting" and removing lateral core elements 1 l and controlling the casting stripping members, known per se, are also arranged within the half-die 7.

In operation, after injecting the molten metal through the duct2 and maintaining the metal pressure throughout the setting period, the control unit 10 is actua'ted for disassembling the core elements 10, by means of a cylinder and piston actuator 10; and then releasing these elements by raising the unit 10 along the slideways 9 by means of another cylinder and piston actuator 9 The mode of operation of this unit 10 will be described more in detail presently in the specification.

The backward movement of movable tray 6 along the frame structure 5 is attended by the opening of the mold due to the movement of the movable mold element 7 away from the fixed mold element 3, the cluster of castings remaining attached to the movable element The bottom element 8 of the mold is then released along the slideways 8 and thecluster of castings is gripped by a discharge clamp 11;, and released from the mold cavities 7,. by retracting the core members 11, and pushing the ejectors 11 by means of the aforesaid mechanism 11.

A device of the type illustrated in FIG. 1, equipped with a pair of units 10 disposed side byside, is designed for producing a cluster of four castings 1-2 interconnected through a duct 13 as shown in FIG. 2. As a consequence of the pre-heating of the castingduct 8 the quantity of injected metal depends only on the capacity of the furnace 1; in any case, the number of castings mentioned in this example concerning but a specific form of embodiment should not be construed as limiting the invention. In fact, by using a different arrangement of the means implemented by the present invention it is also possible to retract

members

8 and 10 simultaneously and to insert the mechanisms 11 into fall into a discharge pit substituted for theclamp' discharge means mentioned embodiment.

In the low-pression chill-casting device illustrated in the preceding form of diagrammatically in FIG. 3 and designed for casting pistons arranged in clusters, the pistons are disposed by pairs assembled by their tops along two rows, and the casting furnace is similarly of the low-pressure type 1 connected through a feed duct 2 to a fixed half-die 3 having mold cavities 3 formed therein; this fixed halfdie 3 is mounted to a fixed support 4 rigid with a frame structure 5. Another half-die 3 rotatably movable about a shaft 3 completes the mold structure 3. A movable tray 6 slidably mounted on the frame structure 5 receives the other half-die 7 having a plurality of mold cavities 7, and equipped symmetrically with supports 9 provided with slideways 9,. Control Control units 10 are also provided for assembling and disassembling the core elements 10, for shaping the inner cavities of the pistons, these units 10 being also movable along slideways 9 In operation, after the molten metal has been injected through the casting duct 2 and set inthe mold cavities, the control units 10 are adapted simultaneously to disassemble and retract the core elements 10 and then control the backward movement of tray 6 along the frame structure 5 for releasing the die section 7. Then the removal of the core elements from half-die 3 will permit the upward movement of the mold element 3 carrying the cluster of castings 12 by rotating through about 90 about the shaft 3 the gripping of said cluster by means of a handling clamp (not shown), the release thereof in relation to mold element 3 by means of ejectors, and finally its discharge. As an alternative solution, the mold element 3 may be raised separately after i the removal of the core members adapted to form the piston spindle bores, the cluster of castings remaining in the mold cavities 3 of the fixed half-die 3 from which it is subsequently removed by ejectors so as to fall into the discharge pit.

FIG. 4 shows a cluster of eight castings 12 thus obtained and interconnected by a casting sprue 13, these castings being assembled by pairs and in opposition. The pistons of each pair are subsequently separated by cutting along the dash-lines 13 With a sprue 13 substantially equivalent to that of the example shown in FIG. 2, this solution permits the casting of twice as many pistons. The limitations of the number of castings by injection are the same as those mentioned in connection with the preceding example.

FIG. 5 illustrates a control unit for assembling and disassembling five-core elements for constituting the inner cavity of two pistons disposed side by side, as well as the mold elements of the example shown in FIG. 1; in the arrangement of FIG. 5 there are a central core member 14 and two lateral core members 15 constituting in conjunction with two other lateral core members 16 (not visible in this Figure) the configuration of the innercavity of piston 12.

The central core member 14 is rigid with a mounting head 17 permitting assembly thereof with a connecting member 18 rigid with the piston rod 19 of an actuator 10 controlling the mechanism. Associated with this piston rod 19 are a ring 20 and a rod 21 actuating the control means of the aforesaid actuator 9 at the end of the stroke of actuator 10 The end of rod 19 is hollow and adapted to house a coil compression spring 22 actuating in turn a push member 23 anda rod 24 bearing against an assembly comprising two pivot members 25 so as to urge said rod against core members 15. These core members are rigid with the trunnion 26 and rack members 27 in meshing engagement with pinions 28 driven from the rack end 29 of the socket 30.

A spring-loaded ball 31 housed in a radial bore 37 in member 18 is adapted to slide along a groove 32 of socket 30. A hole 33 at the end of this groove permits, by snapping the. ball 31 into it, detent-positioning the socket and member 18 in the upper position of said member 18.

The actuator 9 is adapted to operate a slide 34 rigid with the frame structure 35 of control head 10 to raise the latter.

FIG. 6 illustrates an assembly comprising two units 10A and 10B mounted side by side on a common frame structure 9. Lateral openings 36 formed in the body 35 illustrated in unit 108 permit the access to control holes 37 and the rotation of member 18 in the socket 30 by moving the ball 31 out from its groove 32.

The unit 10A shows the relative positions of the different component elements of the mechanism at the levels of the various sections.

The different movements of the control mechanism, in the case of a three-element core unit, are illustrated in FIGS. 7 and 8. As in the preceding case the assembly comprises a central core element 14 reproducing in conjunction with a pairof lateral core elements 15 the inner shape of the cavity of piston 12. The mounting head 17 of core element 14 fits into a connecting member 18 similar to the five-element core mounting described in the foregoing, all the other component elements of the mechanism being also similar to those of the preceding example.

' In operation, after the injection and setting of the casting 12, the central core member 14 is retracted by means of its operative connection 17 with the intermediate member 18 coupling said core member 14 to the piston rod 19. When the core member '14 is in position 14,, as shown in FIG. 8, the detentpositioning ball- 31 (FIG. 5) having moved along the groove 32 engages the hole 33 in member 30, thus moving the latter to the upper position 30 the mechanism comprising pinions 28, racks 27 and shafts 26 causing the core members 15 to be released in position 15 from the cavity of casting 12. At the end of the upward movement the rod 19 of actuator 10 controls through a rod 21 an electric limit switch (not shown) monitoring a solenoid-operated hydraulic valve (not shown) controlling the movement of actuator9 (FIG. 5) for raising the complete unit 10 and eventually releasing the core members l5from the cavities of castings 12.

All the sequences of movements of said actuators are obtained by using limit switches monitoring solenoidoperated hydraulic valves according to a technique well known per se.

A play of at least 2 mm is provided between thetwo core members 15 in position 15,, to avoid any contact between their assembling faces 15, 7

Of course, the reverse sequence of operations will reassemble the

core members

14 and 15 in cavity 12 before performing another injection step. The stacking of core members on the bearing faces 38 and 39 of halfdie 3 will avoid any possibility of jamming and wear by friction on the contact faces 15 FIGS. 9 and 10 are section's taken along two orthogonal planes, showing the mechanism obtaining in the case of a five-element core assembly of the type shown in FIG. 5, i.e., a central core member 14 having lateral extensions 16'and covered on either side by another pair of lateral core members 15. The half-sections clearly show the relative movements of the component elements of this mechanism.

In contrast to FIGS. 9 and 10 showing a typical example of an adaptation to relatively small castings (pistons), FIGS. 11 and 12 show the same sections and the same movements in the case of larger castings, in order to illustrate the adaptability or flexibility of the mechanism.

FIG. 13 shows in detail the assembling of the lateral core elements 15 with the shafts 2'6 and racks 27. FIG. 14 shows the locking action resulting from the engagement of dovetailed ends of core members 15 in racks 27 and the wedging thereon by the bevelled ends of shafts 26.

FIG. 15 illustrates the detail of the assembling of pivot means 25 of core members 16 with the central core member 14. The members 25 assembled by a common shaft 40 are urged against the bottom 14,, of the central opening of core member 14 by the pressure exerted on rod 24 through the assembling head 17 by push member 23. FIG. 16 shows the assembly of the lateral core members 16, pivotally mounted on shafts 41, with the pair of pivot members 25 engaging the shafts 41 and assembled by means of a central pin 40.

In operation, in the case of a five-element core assembly as shown in FIGS. 9 to 12 inclusive, after the injection and setting of the molten metal to form the castings 12 the central core member 14 is retracted by the action of piston rod 19 of actuator 10 exerted on the connecting member 18 and on the mounting head 17. When the core member 14 has moved from position 14,, to position 14 it engages and pushes the rounded studs 16, of core members 16 to pivot these members about the shafts 41, thus freeing the ends of these core members and moving same from position 16,, to position 16 The face 14 of the central rectangular opening of core member 14 then engages the members 25 and carries along the core members 16 during its release movement. Then, the snap engagement of ball 31 (FIG. 5) into hole 33 of socket 30, after its movement along the groove 32, will move the member 30 and release the lateral core members according to the same process as in the case of a three-element core already explained hereinabove. As core member 14 moves to position 14,, (see half-section of FIGS. 9 to 12) the core members 15 move from position 15,, to position 15,,, thus permitting the final release of the assembly under the control of actuator 9 The rotation of member 18 by means of the control holes 37, as a consequence of the disengagement of ball 31 from its groove 32 will permit of positioning the member 18 in alignment with the opening 36 (FIG. 6) and also with the lateral opening 42 (FIG. 5) of socket 30. Under these conditions, the member can be released laterally along the T-sectioned fitting grooves formed in the piston rod of actuator 19 and of assembling head 17, so that the central core member 14 can be retracted. The core members 15 are disassembled beforehand through the backward movements of shafts or pivot pins 26, and the core members 16 are disassembled by the lateral removal, through

openings

42 and 36, of shaft 40 and members 25. With this combination it is possible to replace the core member assemblies very rapidly, for instance in case of failure or damage, or when changing the type of tool, so that the control units 10 constitute standard mounting heads adaptable to a great number of combinations and applications.

We claim:

1. An automatically operated multiple cavity die device for low pressure casting, comprising:

a chill-casting mold comprising two half-dies, one of said half-dies being fixed and the other of said halfdies being movable, both half-dies having an even numbered plurality of mold cavities therein aligned in a joint plane of said half-dies;

a casting feed duct communicating with the mold cavities in the fixed half-die;

injection means for injecting material into said mold cavity through said feed duct; means for moving the movable half-die toward and awa from the fixed half-die; retrac able core members oriented for entry into said mold cavities substantially along said joint plane of said half-dies;

automatic core assembly means for performing assembling and disassembling movements of said core members in a pair of two mold cavities, said core assembly means including only one piston actuator for actuating said assembly.

2. A device according to claim 1, additionally comprising ejection means on the movable half-die, and an automatic handling clamp for discharging clusters of castings from said movable half-die.

3. A device according to claim 1, additionally comprising ejection means on the fixed half-die, for discharging castings into a discharge pit after stripping and retracting the other half-die and the core members.

4. A device according to claim 1, wherein the halfdies define engine piston castings disposed symmetrically by pairs in opposition with joined heads, two symmetrical rows of automatic core assembly means being provided for actuating the core elements adapted to shape the inner cavities of said pistons, the fixed halfdie comprising a pivoting portion for clearing the casting duct.

5. A device according to claim 1, wherein the actuator associated with the automatic core assembly means has the end of a piston rod connected to an intermediate connecting member rigid with a central core member of the device.

6. A device according to claim 5, wherein the automatic assembly means comprises a socket also movable in translation along the axis of said actuator, said connecting member being slidably mounted in said socket and held against rotation by a spring-loaded ball sliding in an inner groove formed in said socket and provided at its end with a hole for locking said socket against translation in relation to said intermediate connecting member.

7. A device according to claim 6, wherein the socket has an end portion formed with rack teeth in meshing engagement with pini'ons driving other rack means assembled by dovetail fitting and lock pins to lateral core elements of the device.

v 8. A device according to claim 1, wherein a five-element core structure is provided for shaping the inner cavities of castings, comprising two core elements constituting extensions of a central core element, said extensions mounted on pivot members, a rod urged against said pivot members by a push member and a spring enclosed in a hollow end portion of the piston rod of said actuator, and cam faces provided on said central core element for rocking said extensions by engaging rounded studs pivotally mounted on pins.

9. A device according to claim 6, wherein said socket V and a frame structure of said automatic assembly

Claims

1. An automatically operated multiple cavity die device for low pressure casting, comprising: a chill-casting mold comprising two half-dies, one of said halfdies being fixed and the other of said half-dies being movable, both half-dies having an even numbered plurality of mold cavities therein aligned in a joint plane of said half-dies; a casting feed duct communicating with the mold cavities in the fixed half-die; injection means for injecting material into said mold cavity through said feed duct; means for moving the movable half-die toward and away from the fixed half-die; retractable core members oriented for entry into said mold cavities substantially along said joint plane of said halfdies; automatic core assembly means for performing assembling and disassembling movements of said core members in a pair of two mold cavities, said core assembly means including only one piston actuator for actuating said assembly.

4. A device according to claim 1, wherein the half-dies define engine piston castings disposed symmetrically by pairs in opposition with joined heads, two symmetrical rows of automatic core assembly means being provided for actuating the core elements adapted to shape the inner cavities of said pistons, the fixed half-die comprising a pivoting portion for clearing the casting duct.

7. A device according to claim 6, wherein the socket has an end portion formed with rack teeth in meshing engagement with pinions driving other rack means assembled by dovetail fitting and lock pins to lateral core elements of the device.

8. A device according to claim 1, wherein a five-element core structure is provided for shaping the inner cavities of castings, comprising two core elements constituting extensions of a central core element, said extensions mounted on pivot members, a rod urged against said pivot members by a push member and a spring enclosed in a hollow end portion of the piston rod of said actuator, and cam faces provided on said central core element for rocking said extensions by engaging rounded studs pivotally mounted on pins.

9. A device according to claim 6, wherein said socket and a frame structure of said automatic assembly means are formed with lateral openings for disassembling said connecting member.