EP0819485B1 - Verfahren, Vorrichtung und Feingiessform zum Giessen zylindrischer Gegenstände - Google Patents

Verfahren, Vorrichtung und Feingiessform zum Giessen zylindrischer Gegenstände Download PDF

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Publication number
EP0819485B1
EP0819485B1 EP19960111597 EP96111597A EP0819485B1 EP 0819485 B1 EP0819485 B1 EP 0819485B1 EP 19960111597 EP19960111597 EP 19960111597 EP 96111597 A EP96111597 A EP 96111597A EP 0819485 B1 EP0819485 B1 EP 0819485B1
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EP
European Patent Office
Prior art keywords
shell
insert
spiny
inserts
shell molding
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP19960111597
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English (en)
French (fr)
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EP0819485A1 (de
Inventor
Akio Shimizu
Takehiro Nagaya
Taiti Yoshikawa
Yoshio Kashiwagi
Masaru Usui
Toshihiro Nishiwaki
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Honda Motor Co Ltd
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Honda Motor Co Ltd
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Publication date
Application filed by Honda Motor Co Ltd filed Critical Honda Motor Co Ltd
Priority to EP19960111597 priority Critical patent/EP0819485B1/de
Priority to DE1996621922 priority patent/DE69621922T2/de
Publication of EP0819485A1 publication Critical patent/EP0819485A1/de
Application granted granted Critical
Publication of EP0819485B1 publication Critical patent/EP0819485B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C7/00—Patterns; Manufacture thereof so far as not provided for in other classes
    • B22C7/005—Adjustable, sectional, expandable or flexible patterns

Definitions

  • the present invention relates to a shell molding apparatus according to claim 1 and a method of casting using the shell mold manufactured by the shell molding apparatus.
  • the shell molding apparatus is for molding a shell for casting a cylindrical product such as a sleeve for use in a cylinder block.
  • a plurality of cylindrical sleeves 81 are manufactured by casting, and the sleeves 81 are then disposed into the cavity of a die casting die. Subsequently, a molding aluminum alloy is charged into the cavity to cast the cylinder block 80.
  • the sleeves 81 For reliable engagement between the sleeves 81 and a block body 82 of aluminum alloy, the sleeves 81 have many protrusions on the surface thereof. According to a conventional practice, such cylindrical sleeves are cast one by one during a casting process using a sand mold formed of greensand or sand which hardens with time.
  • the conventional method of manufacturing sleeves requires much labor, is inefficient, and further has a drawback that it cannot be used to mass-produce double sleeves or sleeves of a higher multiple.
  • a first object of the present invention is to provide a shell molding apparatus capable of molding with ease and at low cost a shell mold which enables the mass production of at least double sleeves having many protrusions at the undercut portion thereof.
  • a second object of the present invention is to provide a shell molding apparatus capable of molding with ease a shell mold which can suppress the deformation of cast sleeves caused by solidification and contraction of molten metal.
  • a third object of the present invention is to provide a casting method using a shell mold which can reduce the number of manufacturing steps as compared to a conventional casting method using a desertion core, which is left shell mold and ejected together with the shell mold.
  • a plurality of sleeve forming portions are provided continuously.
  • at least an endmost sleeve forming portion located adjacent to a subrunner portion has modified shape for compensating the deformation of cast sleeves caused by solidification and contraction of molten metal.
  • the shell mold according to the present invention has the following structure.
  • a plurality of sleeve forming portions are provided continuously.
  • at least a subrunner-side endmost sleeve forming portion has a modified shape as follows.
  • the axis. "a'" of a half portion of the endmost sleeve forming portion with respect to its central point Q1 is inclined inwardly from a reference line S' by a predetermined angle ⁇ 1
  • the axis "b'" of the other half portion is inclined outwardly from the reference line S' by a predetermined angle ⁇ 2.
  • shell molding apparatus includes an upper die and a lower die which constitute a die set for molding a shell mold.
  • said lower die comprises a plurality of shell molding inserts, each having the shape of a halved cylinder, spiny inserts receiving recesses which are formed in undercut portions formed by curved surfaces of adjacent shell molding inserts a spiny insert movably located within each spiny insert receiving recesses, each spiny insert having a surface of the same curvature as the curved surface of the shell molding insert and provided with many protrusions on the surface, each said spiny insert is actuated by a spiny insert actuating means comprising a withdrawal pin connected to said spiny insert, a slide block, for actuating the withdrawal pin, and an actuator cylinder, for actuating the slide block.
  • the upper die is formed such that the body of the upper die has a plurality of continuously formed recesses corresponding to the plurality of shell molding inserts of the lower die, thereby forming a
  • a cavity in the shape of a shell mold is defined between the recesses formed in the cavity of the upper die and the shell molding inserts of the lower die such that the portion of the space corresponding to the subrunner side end portion of the sleeve forming portion has a modified shape so as to compensate for deformation of a cast sleeve caused by solidification and contraction of molten metal.
  • the shell molding apparatus includes a die set for molding a shell mold which is composed of an upper die and a lower die and has the following structure.
  • the lower die has a plurality of shell molding inserts, each having the shape of a halved cylinder.
  • an endmost shell molding insert is modified in shape such that the axis "a" of a half portion of the shell molding insert located on the side of a lateral M/C centerline 01 with respect to the central point Q of the shell molding insert is inclined inwardly from a reference line S by a predetermined angle ⁇ 1, the reference line S being in parallel with a longitudinal M/C centerline 02 and that the axis "b" of the other half portion of the shell molding insert located on the side opposite to the lateral M/C centerline 01 with respect to the central point Q is inclined from the reference line S by a predetermined angle ⁇ 2.
  • the thus formed shell molding inserts are inserted into the recesses formed in the cavity of the upper die, thereby forming a space in the shape of a sand mold to be molded between the shell molding inserts and the recesses.
  • the shell molding apparatus further includes spiny insert actuating means for projecting and retracting the spiny inserts, upper die moving means for causing the upper die to contact and part from the lower die, and ejecting means for parting a molded shell mold from the lower die.
  • spiny insert actuating means for projecting and retracting the spiny inserts
  • upper die moving means for causing the upper die to contact and part from the lower die
  • ejecting means for parting a molded shell mold from the lower die.
  • the spiny insert actuating means has the following structure.
  • a slide block positioning arm is fixed to the lower die at each of both end portions of the lower die, and a cylinder holding member is fixed to the lower die at the central portion of each of both longer sides of the lower die.
  • One slide block positioning arm holds one slide block such that the slide block can move toward the spiny inserts.
  • Another slide block positioning arm holds another slide block such that the slide block can move toward the spiny inserts.
  • the slide blocks hold the end portions of a plurality of withdrawal pins connected to the spiny inserts.
  • One actuator cylinder for actuating the one slide block is provided on one cylinder holding member, and another actuator cylinder for actuating the other slide block is provided on another cylinder holding member.
  • protrusions are formed on the curved surface of the spiny insert by electric spark machining.
  • a casting method using a shell mold comprises the steps of: reversely copying many protrusions of a spiny insert to an inner surface of a halved shell mold at the undercut portion of the inner surface by moving a spiny insert provided in a lower die, thereby forming many depressions in the undercut portion; parting the halved shell mold from the lower die: disposing a plurality of bore forming cores in the halved shell mold; engaging the halved shell mold and another halved shell mold each other by mating the halved shell molds with each other at mating surfaces thereof, thereby forming a shell mold for casting; and performing casting using the thus formed shell mold .
  • Fig. 1 is a partially sectioned plan view of a shell mold.
  • Fig. 2 is a cross-sectional view along line AA-AA of Fig. 1.
  • Fig. 3 is a cross-sectional view along line BB-BB of Fig. 1.
  • Fig. 4 is a plan view of a sleeve forming portion located on the subrunner side, and
  • Fig. 5 is a side view of the sleeve forming portion.
  • a shell mold M is formed using halved shell molds 70 molded by a shell molding apparatus. That is, the halved shell molds 70 are bonded together using adhesive applied to their mating surfaces 70A, and four bore forming cores 71 are disposed therebetween, thereby completing the shell mold M.
  • the shell mold M has a subrunner portion 73 and quadruple-sleeve forming portions 74.
  • a molten aluminum alloy is supplied into the shell mold M to cast a quadruple-sleeve W.
  • the subrunner portion 73 has a thicker wall of molten metal than the quadruple-sleeve forming portion 74. Accordingly, molten metal at the subrunner portion 73 shrinks more than that at the quadruple-sleeve forming portion 74 while the molten metal solidifies. This shrinkage cannot be restricted because the shell mold M Is made of sand.
  • the end portion of a solidified quadruple-sleeve adjacent to the subrunner portion 73 has a greater shrinkage than the other end portion.
  • the quadruple-sleeve deforms into an inverted trapezoidal shape.
  • the design of the shell mold according to the present invention takes the above-described shrinking phenomenon into consideration. That is, the end portion of the quadruple-sleeve forming portion 74 adjacent to the subrunner 73 is shaped to compensate for the shape of deformation described above, thereby suppressing the deformation of the solidified quadruple-sleeve caused by the shrinkage of molten metal.
  • a sleeve forming portion 74A of the quadruple-sleeve forming portion 74 adjacent to the subrunner portion 73 has a modified shape as shown in Figs. 4 and 5.
  • the axis "a'" of an upper half portion 75A located above a center point Q1 in Fig. 4 is inclined inwardly (to the right in Fig. 4) from a reference line S' by a predetermined angle 01.
  • the axis "b'" of a lower half portion 75B located below the center point Q1 in Fig. 4 is inclined outwardly (to the left in Fig. 4) from the reference line S' by a predetermined angle ⁇ 2.
  • the sleeve forming portion 74A is inclined at an angle ⁇ such that the end portion of the upper half portion 75A is lower than that of the lower half portion 75B,
  • the sleeve forming portion 74A of the quadruple-sleeve forming portion 74 adjacent to the subrunner portion 73 has a modified shape so as to prevent the occurrence of deformation of the solidified quadruple-sleeve caused by the shrinkage of molten metal.
  • Fig. 9 is a partially sectioned side view of the lower mold unit of the shell molding apparatus according to the present invention.
  • Fig. 10 is a cross-section of the shell molding apparatus along line A-A of Fig. 9.
  • Fig. 11 is a partial cross-section of the shell molding apparatus along line B-B of Fig. 10.
  • Fig. 12 is a partial cross-section of the shell molding apparatus along line C-C of Fig. 10.
  • the shell mold molding apparatus is mainly composed of a lower die 1 and an upper die 2.
  • the lower die I has a die base 4 fixedly disposed on an apparatus base 3.
  • a lower die heating block unit 5 is fixed on the die base 4.
  • a shell molding insert structure 11 is mounted on the lower die heating block unit 5.
  • the lower die heating block unit 5 and the shell molding insert structure 11 constitute the lower die unit.
  • the lower die heating block unit 5 has a heating block 6 having a rectangular shape as viewed from above.
  • Four groups 7 of insert receiving recesses are disposed in rows on the top surface 6A of the heating block 6, two rows on the left half side (MS side) and two rows on the right half side (MP side) as viewed from worker position P.
  • Each group 7 of insert receiving recesses has four insert receiving recesses 8 disposed at a predetermined pitch in the front-rear direction as viewed from the worker position P.
  • a plurality of sand release bores 9 are formed in the bottom portion of the insert receiving recesses 8 such that the sand release bores 9 extend through the heating block 6 to the bottom surface 6B thereof.
  • three pin insertion bores 10 are formed in the heating block 6 obliquely upward from the front side (worker position P; hereinafter “front” refers to the side of the worker position P) to front-side three insert receiving recesses 8, and three pin insertion bores 10 are formed in the heating block 6 obliquely upward from the rear side (opposite to the worker position P; hereinafter “rear” refers to the side opposite to the worker position P) to rear-side three insert receiving recesses 8.
  • Many heater Insertion bores 60 are formed in right and left end portions of the heating block 6. Heaters 61 are inserted into the heater insertion bores 60 (see Fig. 9).
  • the shell molding insert structure 11 has two groups 12 of shell molding inserts in two rows, each group having four shell molding inserts.
  • Each group 12 of shell molding inserts has a front-side shell molding insert 12A, two intermediate shell molding Inserts 12B, and a rear-side shell molding insert 12C.
  • the front-side shell molding insert 12A has an insert body 13 having a semicircular cross-section.
  • the insert body 13 has a rectangular fitting portion 14 at the bottom portion thereof and a flat mating surface 15 at the rear side thereof.
  • a spiny insert receiving recess 16 having a rectangular shape as viewed from above is formed in the insert body 13 at the rear portion thereof.
  • Rod insertion bore portions 17 are formed in the insert body 13 such that they extend from the front surface of the fitting portion 14 to the bottom surface of the spiny insert receiving recess 16.
  • Sand release bores 18 are formed in the insert body 13 such that they extend from the bottom surface of the spiny insert receiving recess 16 to the bottom surface of the fitting portion 14.
  • the front-side shell molding insert 12A may has a modified shape as follows.
  • the axis "a" of a half portion 40A of the front-side shell molding insert 12A located on the side of the lateral M/C centerline 01 with respect to a center point Q in Fig. 6(1) is inclined inwardly (to the right in Fig. 6(1)) from a reference line S by a predetermined angle ⁇ 1, the reference line S being in parallel with a longitudinal M/C centerline 02.
  • the axis "b" of another half portion 40B of the front-side shell molding insert 12A located opposite to the side of the lateral M/C centerline 01 with respect to a center point Q is inclined outwardly (to the left in Fig. 6(1)) from the reference line S by a predetermined angle ⁇ 2.
  • the front-side shell molding insert 12A may be inclined at an angle a such that the end portion of the half portion 40A located on the side of the lateral M/C centerline 01 is lower than that of the half portion 40B located on the side opposite to the lateral M/C centerline 01.
  • Each of the intermediate shell molding inserts 12B has an insert body 13 having a semicircular cross-section.
  • the insert body 13 has a rectangular fitting portion 14 at the bottom portion thereof and a flat mating surface 15 at each of the front and rear sides thereof.
  • a spiny insert receiving recess 16 having a rectangular shape as viewed from above is formed in the insert body 13 at each of the front and rear portions thereof.
  • Rod insertion bore portions 17 are formed in the insert body 13 such that they extend from the front surface of the fitting portion 14 to the bottom surface of the rear-side spiny insert receiving recess 16.
  • rods insertion bore portion 17 are formed in the insert body 13 such that they extend from the rear surface of the fitting portion 14 to the bottom surface of the front-side spiny insert receiving recess 16.
  • Sand release bores 18 are formed in each insert body 13 such that they extend from each spiny insert receiving recess 16 to the bottom surface of the corresponding fitting portion 14. As shown in Fig. 17, the axis c of each intermediate shell molding insert 12B is in parallel with the reference line S, which is in parallel with the longitudinal M/C centerline 02.
  • the front-side shell molding insert 12C has an insert body 13 having a semicircular cross-section.
  • the insert body 13 has a rectangular fitting portion 14 at the bottom portion thereof and a flat mating surface 15 at the front side thereof.
  • a spiny insert receiving recess 16 having a rectangular shape as viewed from above is formed in the insert body 13 at the front portion thereof.
  • Rods insertion bore portion 17 are formed in the insert body 13 such that they extend from the rear surface of the fitting portion 14 to the bottom surface of the spiny insert receiving recess 16.
  • Sand release bores 18 are formed in the insert body 13 such that they extend from the spiny insert receiving recess 16 to the bottom surface of the fitting portion 14.
  • the rear-side shell molding insert 12C may has a modified shape as follows. As shown in Fig. 8, the axis "d" of a half portion 41A of the rear-side shell molding insert 12C located on the side of the lateral M/C centerline 01 with respect to a center point Q is inclined inwardly (to the left in Fig. 8) from a reference line S by a predetermined angle ⁇ 3, the reference line S being in parallel with a longitudinal M/C centerline 02.
  • the axis "e" of a half portion 41B of the rear-side shell molding insert 12C located on the side opposite to the lateral M/C centerline 01 with respect to the center point Q is inclined outwardly (to the right in Fig. 8) from the reference line S by a predetermined angle ⁇ 4.
  • the group 12 of four shell molding inserts is mounted in the group 7 of four Insert receiving recesses provided in the lower die heating block unit 5. That is, the front-side shell molding insert 12A is fitted into the front-side insert receiving recess 8 of the group 7 of four insert receiving recesses and then fixed using bolts. Likewise, the intermediate shell molding inserts 12B are fitted into the intermediate insert receiving recesses 8 of the group 7. The rear-side shell molding insert 12C is also fitted into the rear-side insert receiving recess 8 of the group 7.
  • Adjacent shell molding inserts 12A, 12B, and 12C contact each other at the mating surfaces 15.
  • the spiny insert receiving recess 16 is formed at each undercut portion R which is formed by adjacent curved surfaces of the adjacent shell molding inserts 12A, 12B, and 12C.
  • the sand release bores 18 extending from the spiny insert receiving recesses communicate with the sand release bores 9 provided in the lower die heating block unit 5.
  • the rod insertion bore portions 17 in the front-side shell molding insert 12A and the front-side rod insertion bore portions 17 in each of two intermediate shell molding inserts 12B communicate with front-side three pin insertion bores 10 provided in the lower die heating unit 5.
  • the rod insertion bore portions 17 in the rear-side shell molding insert 12C end the rear-side rod insertion bore portions 17 in each of two intermediate shell molding inserts 12B communicate with rear-side three pin insertion bores 10 provided in the lower die heating unit 5.
  • Spacer blocks 19 are disposed between two rows of groups 12 of shell molding inserts, i.e. between the opposed end surfaces of the opposed shell molding inserts 12A, of the opposed shell molding inserts 12B, and of the opposed shell molding inserts 12C.
  • the spacer blocks are fixed on the lower die heating block unit 5 using bolts.
  • the shell molding inserts 12A, 12B, and 12C in a right-hand group 12 as viewed from the worker position P are fixed at their right-hand ends using right-hand end holding members 20.
  • the shell molding inserts 12A, 128, and 12C in a left-hand group 12 as viewed from the worker position P are fixed at their left-hand ends using left-hand end holding members 21.
  • the right- and left-hand end holding members 20 and 21 are fixed on the lower die heating block unit 5 using bolts.
  • the spiny inserts 22 are inserted into the spiny insert receiving recesses 16 such that they are allowed to project from the recesses and retract thereinto.
  • each spiny insert 22 has an insert body 23.
  • the curved surface 23a of the insert body 23 has the same curvature as the curved surfaces of the front-side, intermediate, and rear-side shell molding inserts 12A, 12B, and 12C.
  • Many protrusions 24 are formed on the curved surface 23a.
  • the insert body 23 is provided with two rods 25, and end of each rod 25 is formed into a threaded portion 25a.
  • Each of the spiny inserts 22 described above is manufactured by machining an insert material block 23-1 shown in Fig. 40 by an electric spark machining process.
  • the insert material block 23-1 has a curved surface 23a-1.
  • the insert material block 23-1 is subjected to electric spark machining as a workpiece 23W, using an electrode 23-2 shown in Fig. 39.
  • the surface 23-2A of the electrode 23-2 is curved concavely so as to correspond to the surface 23S (convexly curved surface 23a-1) of the workpiece 23W to be subjected to electric spark machining.
  • Many recesses and protrusions 24-2 are formed in the curved surface 23-2A.
  • the machining electrode 23-2 and the workpiece 23W are positioned such that the surface 23-2A of the electrode faces the surface 23S to be machined of the workpiece (the spacing between the surface 23-2A and the surface 23S is very narrow, and an insulating liquid such as KEROSINI. water or the like is present therebetween).
  • An impulse voltage of 60-300 V is applied between the machining electrode 23-2 and the workpiece 23W to perform intermittent spark discharge, causing an abnormal consumption phenomenon.
  • the abnormal consumption phenomenon is utilized for reversely copying the recesses and protrusions 24-2 of the machining electrode 23-2 onto the surface 23S of the workpiece 23W, thereby forming many protrusions 24 on the workpiece 23W.
  • the thus manufactured spiny Insert 22 is retractably inserted into the spiny insertion recess 16 while the rods 25 thereof are inserted into the rod insertion bore portions 17.
  • slide block positioning arms 26 are fixed to the die base 4 at the front side thereof, and right and left slide block positioning arms 27 are fixed to the die base 4 at the rear side thereof.
  • a cylinder holding member 28 is fixed to the die base 4 at the intermediate portion of the front side thereof, and a cylinder holding member 29 is fixed to the die base 4 at the intermediate portion of the rear side thereof.
  • Each of the front-side right and left slide block positioning arms 26 has a pair of support portions 30, in which pin bores 31 are formed. The front-side right and left slide block positioning arms 26 hold in place the front-side slide block 32A.
  • the slide block 32A has a long block member 33 having a rectangular cross-section.
  • a pin sliding mechanism 34 is provided at each of both end portions of the block member 33.
  • the pin sliding mechanism 34 has a structure in which guide bushings 35 and 36 are inserted into a bore 33a formed in the block member 33 and that the guide bushings 35 and 36 are held in place by the bushing holders 37 and 38.
  • Two groups of pin insertion bores 39, each having three bores, are formed in parallel with each other in the block member 33 on the right and left sides with respect to the central portion of the block member 33.
  • a pin receiving member 40 is fixed to the block member 33 behind the pin insertion bores 39. Threaded bores 41 are formed in the pin receiving member 40 such that they face the end portions of the pin insertion bores 39.
  • the slide block 32A having the above-described structure is held by the front-side right and left slide block positioning arms 26 while the guide bushings 35 and 36 of the pin sliding mechanism 34 are slidably fitted to slide pins 42 which are supported by a pair of support portions 30.
  • each of withdrawal pins 43 has a threaded bore 43a at the tip end thereof and a polygonal flange 43b at the base end thereof.
  • the withdrawal pins 43 are inserted into the pin insertion bores 39 of the slide block 32 and into the pin insertion bores 10 of the lower die heating block unit 5.
  • the threaded portions 25a of the rods 25 of each spiny insert 22 are screwed into the threaded bores 43a of the withdrawal pins 43, whereby the withdrawal pins 43 are engaged with the spiny insert 22.
  • polygonal washers 40A are inserted into the pin receiving member 40-1.
  • Adjusting bolts 44 are screwed into the threaded bores 41 of the pin receiving members 40, and a spacing "t" is formed between the end surfaces of the adjusting bolts 44 and the end surfaces of the flanges 43b of the withdrawal pins 43 so as to absorb variations in length of the withdrawal pins 43 caused by-thermal expansion.
  • An actuator cylinder 45A is mounted to the front-side cylinder holding member 28, and the piston rod 46A of the actuator cylinder 45A is fixed to the slide block 32A at the central portion thereof.
  • the actuator cylinder 45A, the slide block 32A, and the withdrawal pins 43 constitute front-side spiny insert actuating means.
  • the rear-side slide block 32B has the same structure as the front-side slide block 32A as described below. As in the front-side slide block 32A, the rear-side slide block 328 is held in place by right and left slide block positioning arms 27. Withdrawal pins 43 are inserted into pin insertion bores 39 of the slide block 32B and into the pin insertion bores 10. The threaded portions 25a of the rods 25 of the spiny insert 22 are screwed into the threaded bores 43a of the withdrawal pins 43, whereby the withdrawal pins 43 are engaged with the spiny insert 22.
  • An actuator cylinder 45B Is mounted to the rear-side cylinder holding member 28, and the piston rod 46B of the actuator cylinder 45B is fixed to the slide block 328 at the central portion thereof.
  • the actuator cylinder 45B, the slide block 32B, and the withdrawal pins 43 constitute rear-side spiny insert actuating means.
  • a plurality of eject pin bores 46 are formed in the apparatus base 3, the die base 4, and the lower die heating block unit 5.
  • Eject pins 47 are inserted into the eject pin bores 46.
  • the eject pins 47 are linked together and moved vertically by an ejecting lift mechanism (not shown), thus forming eject means.
  • the upper die 2 has an upper die unit 48, in which, as shown in Figs. 30 to 32, a die parting face 49 of a cavity 50 is formed.
  • the cavity is formed of a plurality of continuous recesses 51 corresponding to the shell molding inserts 12A, 12B, and 12C of the lower die 1.
  • the upper die unit 48 is provided with gates 52, each communicating with each of the recesses 51.
  • Many heater insertion bores 62 are formed through the upper die unit 48 in the front-rear direction, and heaters 63 are inserted into the bores.
  • the upper die 2 is moved vertically by a lift mechanism (not shown).
  • the actuator cylinders 45A and 45B of the lower die 2 are expanded to move the slide blocks 32A and 32B to thereby moving the withdrawal pins 43 until the end surfaces 43F of the withdrawal pins 43 abut against the stepped stop ends 17C of the rod insertion bore portions 17.
  • the spiny inserts 22 engaged with the withdrawal pins 43 advance, so that the curved surfaces 23a of the spiny inserts 22 coincide with the surfaces of the front-side, intermediate, and rear-side shell molding inserts 12A, 12B, and 12C.
  • many protrusions 24 on the curved surfaces 23a project.
  • the above-mentioned lift mechanism operates to lower the upper die 2 until the parting face 49 of the upper die unit 48 and the parting face 65 of the lower die unit 64 mate each other.
  • the shell molding inserts 12A, 12B, and 12C are inserted into corresponding recesses 51 of the cavity 50, whereby a space H having the shape of a sand mold to be molded is formed between the shell molding inserts and the recesses.
  • shell sand (mixture of silica sand and thermosetting polymeric material) is charged into the space H through the plurality of gates 52 provided in the upper die unit 48.
  • the heaters 61 and 63 provided in the upper and lower dies 1 and 2 are energized to heat the upper and lower die units 48 and 64 and shell molding inserts 12A, 12B, and 12C to a temperature of about 350°C.
  • the shell sand hardens to form the shell mold 70.
  • the heaters 61 and 63 are de-energized.
  • the upper die 2 is raised by the lift mechanism to part the upper die 2 from the lower die 1.
  • the shell mold 70 is attached to the shell molding inserts 12A, 12B, and 12C of the lower die 1.
  • the actuator cylinders 45A and 45B of the lower die 2 are contracted to retreat the slide blocks 32A and 32B to thereby retract the spiny inserts 22 via the withdrawal pins 43.
  • the protrusions 24 are about 2 mm long, the amount of retraction of the spiny inserts 22 is about 5 mm.
  • the ejector lift mechanism operates to raise the eject pins 47 to push up the shell mold 70 to part it from the lower die 1.
  • the obtained shell mold 70 is half of a required shell mold and is provided, at the undercut portions on the inner surface thereof. with many depressions which are formed by reversely copying many protrusions 24 of the spiny inserts 22.
  • two halved shell molds 70 are engaged each other by bonding them at mating surfaces 70A while four bore forming cores 71 are placed therebetween.
  • the sleeve forming portion 74A of the quadruple-sleeve forming portion 74 adjacent to the subrunner portion 73 is previously modified in shape as shown in Figs. 4 and 5.
  • the axis "a'" of the upper half portion 75A located above the center point Q1 in Fig. 4 is inclined inwardly (to the right in Fig. 4) from the reference line S' by a predetermined angle 01.
  • the axis "b'" of the lower half portion 75B located below the center point Q1 in Fig. 4 is inclined outwardly (to the left in Fig. 4) from the reference line S' by a predetermined angle ⁇ 2.
  • the sleeve forming portion 74A is inclined at an angle ⁇ such that the end portion of the upper half portion 75A is lower than that of the lower half portion 75B.
  • the shell mold is transferred to a casting site, where molten aluminum alloy is poured into the shell mold to cast a quadruple-sleeve W shown in Fig, 36.
  • Many protrusions 24' are formed on the sleeve W at undercut portions R' thereof.
  • the sleeves W are embedded in an aluminum alloy so as to manufacture a cylinder block S shown in Fig. 37.
  • the flow chart of Fig. 33 shows the steps of molding the above-described shell mold and performing by using the shell mold.
  • step S1 of the flow chart many protrusions 24 of the spiny inserts 22 provided in the lower die 1 are reversely copied to the shell mold 70 at the undercut portions of the inner surface thereof by advancing the spiny inserts 22, thereby forming many depressions in the undercut portions.
  • the halved shell mold 70 is parted from the lower die 1, and then four bore forming cores 71 are set in place in the halved shell mold 70.
  • the halved shell mold 70 and another halved shell mold 70 are engaged each other by bonding them at their mating surfaces 70A. whereby a shell mold for casting is prepared.
  • the shell mold is transferred to the casting site.
  • molten aluminum alloy is poured into the shell mold so as to cast the quadruple-sleeve W.
  • the flow chart of Fig. 34 shows steps of performing casting by using a desertion core.
  • desertion cores having many protrusions are formed.
  • the prepared desertion cores are transferred to the next shell molding step.
  • the desertion cores are set In place in a master mold, and many protrusions of the desertion core are reversely copied to a shell mold at the undercut portions of the inner surface thereof, thereby forming many depressions in the undercut portions.
  • the halved shell mold is parted from a lower die, and then four bore forming cores are set in place in the halved shell mold.
  • the halved shell mold and another halved shell mold are engaged each other by bonding them at their mating surfaces, whereby a shell mold for casting is prepared.
  • the shell mold is transferred to a casting site.
  • molten aluminum alloy is poured into the shell mold to cast a quadruple-sleeve W.
  • the proposed method represented by the flow chart of Fig. 33 does not require the step of forming the desertion core having many protrusions (step S1 of Fig. 34), the step of transferring the desertion core (step S2 of Fig. 34), and the step of setting in place the desertion core in the master mold (step S3 of Fig. 34).
  • the shell mold according to the present invention has a structure in which a plurality of sleeve forming portions are continuously provided and In which, of the sleeve forming portions, at least the subrunner-side sleeve forming portion has a modified shape at the end portion thereof such that the modified shape compensates for deformation of a cast sleeve caused by solidification and contraction of molten metal.
  • the shell mold of the present invention can be used for mass production of double sleeves or sleeves of a higher multiple and can suppress deformation of cast sleeves caused by solidification and contraction of molten metal, thereby enabling the casting of deformation free sleeves.
  • the shell mold described has a structure in which a plurality of sleeve forming portions are continuously provided and in which, of the sleeve forming portions, at least the endmost sleeve forming portion adjacent to the subrunner portion 73 has a modified shape as follows.
  • the axis "a'" of one half portion with respect to the center point Q1 is inclined inwardly from the reference line S' by a predetermined angle ⁇ 1.
  • the axis "b'" of the other half portion is inclined outwardly from the reference line S' by a predetermined angle ⁇ 2.
  • the shell molding apparatus can easily manufacture, without using desertion cores, a halved shell mold in which many protrusions of spiny inserts are reversely copied to the inner surface of the halved shell mold at the undercut portions, thereby forming many depressions in the undercut portions.
  • a halved shell mold in which many protrusions of spiny inserts are reversely copied to the inner surface of the halved shell mold at the undercut portions, thereby forming many depressions in the undercut portions.
  • a die set for molding a shell mold is composed of an upper die and a lower die.
  • the lower die is composed of a plurality of shell molding inserts, each having the shape of a halved cylinder, which are inserted into recesses provided in the cavity of the upper die, thereby forming a space having the shape of a shell mold to be molded between the upper and lower dies.
  • the space has a shape corresponding to the shape of the shell mold in which the subrunner-side sleeve forming portion of the space has a modified shape for compensating for deformation of cast sleeves caused by solidification and contraction of molten metal.
  • the shell molding apparatus can mold a shell mold capable of mass-producing double sleeves or sleeves of a higher multiple and suppressing deformation of cast sleeves caused by solidification and contraction of molten metal.
  • a die set for molding a shell mold is composed of an upper die and a lower die.
  • the lower die is composed of a plurality of shell molding inserts, each having the shape of a halved cylinder.
  • an endmost shell molding insert is modified in shape as follows.
  • the axis "a" of one half portion of an endmost shell molding insert located on the side of the lateral M/C centerline 01 with respect to the center point Q is inclined inwardly from the reference line S by a predetermined angle ⁇ 1, the reference line S being in parallel with the longitudinal M/C centerline 02.
  • the axis "b" of the other half portion of the endmost shell molding insert is inclined outwardly from the reference line S by a predetermined angle ⁇ 2.
  • the shell molding inserts are inserted into recesses provided In the cavity of the upper die, thereby forming a space having the shape of a sand mold to be molded between the upper and lower dies.
  • the proposed shell molding apparatus can mold a shell mold capable of mass-producing double sleeves or sleeves of a higher multiple and suppressing deformation of cast sleeves caused by solidification and contraction of molten metal.
  • the casting method using the shell mold according to the present invention does not require the step of forming desertion cores having many protrusions, the step of transferring the desertion cores, and the step of setting in place the desertion cores in a master mold as required in a conventional casting method using desertion cores.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Molds, Cores, And Manufacturing Methods Thereof (AREA)

Claims (7)

  1. Eine Schalenformvorrichtung, welche ein oberes Formteil (2) und ein unteres Formteil (1) aufweist, die ein Formteil-Set zum Formen einer Schalenform (70) bilden, wobei das untere Formteil (1) eine Mehrzahl von Schalenformeinsätzen (12A, 12B, 12C), wobei jeder die Form eines halben Zylinders hat, Ausnehmungen (16) zur Aufnahme eines Dorneinsatzes, welche in eingeschnittene Bereiche (R) eingeformt sind, die durch gekrümmte Oberflächen von benachbarten Schalenformeinsätzen ausgebildet sind, und einen Dorneinsatz (22) aufweist, welcher bewegbar innerhalb einer jeden Ausnehmung zur Aufnahme eines Dorneinsatzes (16) angeordnet ist, wobei jeder Dorneinsatz (22) eine gekrümmte Oberfläche (23a) mit derselben Krümmung wie die gekrümmte Oberfläche der Schalenformeinsätze (12A, 12B, 12C) aufweist und mit vielen Vorsprüngen (24, 24') auf der Oberfläche (23a) versehen ist, wobei der Dorneinsatz durch eine Einrichtung zum Bewegen des Dorneinsatzes bewegbar ist, welche einen Rückzugsstift (43) aufweist, welcher mit dem Dorneinsatz (22), einem Gleitschlitten (32A, 32B) zum Bewegen des Rückzugsstiftes (43) und einem Antriebszylinder (45A, 45B) zum Bewegen des Gleitschlittens (32A, 32B) verbunden ist.
  2. Schalenformvorrichtung nach Anspruch 1, wobei das obere Formteil (2) so ausgestaltet ist, dass ein Körper des oberen Formteils (2) eine Vielzahl von sich fortsetzenden Ausnehmungen (51) aufweist die der Vielzahl von Schalenformeinsätzen (12A, 12B, 12C) des unteren Formteils (1) entsprechen und dabei eine ununterbrochene Kammer (50) zwischen dem oberen und dem unteren Formteil (1, 2) ausformen.
  3. Schalenformvorrichtung nach Anspruch 2, wobei eine Kammer in einer Form einer Schalenform zwischen den Ausnehmungen (51) definiert ist, welche in eine Kammer des oberen Formteils (2) und die Schalenformeinsätze (12A, 12B, 12C) des unteren Formteils (1) eingeformt sind, so dass ein Bereich des Zwischenraumes (4), der einem Endbereich (74A) eines Giesskanalbereiches des die Hülse bildenden Bereiches (74) entspricht, eine veränderte Form aufweist, so dass die Achse (a) des halben Bereiches (40A) der Schalenformeinsätze (12A, 12B), welcher auf der Seite einer lateralen (M/C) Mittellinie (01) hinsichtlich eines mittigen Punktes (Q) des Schalenformeinsatzes (12A, 12B) angeordnet ist, von einer Referenzlinie (S) aus um einen vorgegebenen Winkel (1) nach innen geneigt ist, wobei die Referenzlinie (S) zu einer längsgerichteten M/C Mittellinie (02) parallel verläuft, und dass die Achse (b) eines anderen halben Bereiches (40B) des Schalenformeinsatzes, welcher auf einer der lateralen (M/C) Mittellinie (01) gegenüberliegenden Seite hinsichtlich des mittigen Punktes (Q) angeordnet ist, von der Referenzlinie (S) aus um einen vorgegebenen Winkel (2) geneigt ist, und somit sind die geformten Schalenformeinsätze (12A, 12B) in die Ausnehmungen (51) eingesetzt, die in der Kammer (50) des oberen Formteils (2) eingeformt sind, und dadurch ist ein Zwischenraum (H) in einer Form einer Sandform ausgebildet, welche zwischen den Schalenformeinsätzen (12A, 12B) und den Ausnehmungen geformt werden soll.
  4. Schalenformvorrichtung nach Anspruch 1, welche desweiteren eine Bewegungseinrichtung zum Bewegen des oberen Formteils auf weist, welche bewirkt, dass das obere Formteil (2) mit einem Teil des unteren Formteils (1) in Kontakt kommt, und eine Auswerfereinrichtung zum Trennen einer geformten Schalenform von dem unteren Formteil (1).
  5. Schalenformvorrichtung nach Anspruch 1, wobei die Einrichtung zum Bewegen des Dorneinsatzes eine Ausgestaltung aufweist, wobei:
    ein Arm (26, 27) zum Positionieren des Gleitschlittens an dem unteren Formteil (1) an jedem der beiden Endbereiche des unteren Formteils (1) befestigt ist, und ein Element (28, 29) zum Halten eines Zylinders an dem unteren Formteil (1) in einem mittigen Bereich an jeder der beiden längeren Seiten des unteren Formteils (1) befestigt ist;
    ein Arm (26) zum Positionieren des Gleitschlittens hält einen Gleitschlitten (32A), so dass sich der Gleitschlitten (32A) in Richtung der Dorneinsätze (22) bewegen kann;
    ein anderer Arm (27) zum Positionieren des Gleitschlittens hält einen anderen Gleitschlitten (32B), so dass sich der Gleitschlitten (32B) in Richtung der Dorneinsätze (22) bewegen kann;
    der eine und der andere Gleitschlitten (32A, 32B) halten Endbereiche einer Vielzahl von Rückzugsstiften (43), welche mit den Dorneinsätzen (22) verbunden sind;
    ein Antriebszylinder (45A) zum Bewegen des einen Gleitschlittens (32A) ist an einem Element (28) zum Halten eines Zylinders vorgesehen; und
    ein anderer Antriebszylinder (45B) zum Antreiben des anderen Gleitschlittens (32B) ist an einem anderen Element zum Halten eines Zylinders vorgesehen.
  6. Schalenformvorrichtung nach Anspruch 1, wobei viele Vorsprünge (24, 24') auf einer gekrümmten Oberfläche (23a) des Dorneinsatzes (22) durch elektro-erosive Bearbeitung eingeformt sind.
  7. Ein Giessverfahren unter Verwendung der Schalenform, welche durch eine Schalenformvorrichtung nach einem der vorangehenden Ansprüche hergestellt wurde, umfasst folgende Schritte:
    das Einformen von vielen Vorsprüngen (24, 24') eines Dorneinsatzes (22) in eine Schalenformhälfte (70) in einem ausgehöhlten Bereich (R) der inneren Oberfläche durch Bewegen eines Dorneinsatzes (22), begründet durch das folgende Verfahren, bei dem das untere Formteil (1) eine Vielzahl von Schalenformeinsätzen (12A, 12B, 12C) aufweist, wobei jeder die Form eines halben Zylinders besitzt, Ausnehmungen (16) zur Aufnahme eines Dorneinsatzes, welche in eingeschnittenen Bereichen (R) eingeformt sind, die durch gekrümmte Oberflächen von benachbarten Schalenformeinsätzen ausgebildet werden, und Dorneinsätze (22), welche innerhalb der Ausnehmungen (16) zur Aufnahme eines Dorneinsatzes bewegbar sind, wodurch viele Vertiefungen in dem ausgehöhlten Bereich (R) geformt werden;
    das Trennen der Schalenformhälfte (70) von dem unteren Formteil (1);
    das Anordnen einer Vielzahl von Kernen (71), welche eine Bohrung bilden, in der Schalenformhälfte (70);
    das Zusammenfügen der Schalenformhälfte (70) und einer anderen Schalenformhälfte durch Aneinanderlegen der Schalenformhälften an die andere an zusammenpassenden Oberflächen (70A) der halben Schalenformhälften, wodurch eine Schalenform zum Giessen geformt wird; und
    das Ausführen eines Giessverfahrens, wobei Alluminiumlegierung in die so geformte Schalenform gegossen wird.
EP19960111597 1996-07-18 1996-07-18 Verfahren, Vorrichtung und Feingiessform zum Giessen zylindrischer Gegenstände Expired - Lifetime EP0819485B1 (de)

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EP19960111597 EP0819485B1 (de) 1996-07-18 1996-07-18 Verfahren, Vorrichtung und Feingiessform zum Giessen zylindrischer Gegenstände
DE1996621922 DE69621922T2 (de) 1996-07-18 1996-07-18 Verfahren, Vorrichtung und Feingiessform zum Giessen zylindrischer Gegenstände

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