FR2652526A1 - DEVICE FOR MANUFACTURING LIGHT METAL PISTONS FOR INTERNAL COMBUSTION ENGINES. - Google Patents

Abstract

a) Device for manufacturing light metal pistons for internal combustion engines. b) Support elements (14, 15) are provided which are arranged in the recess (17) of the molding tool (5,9,10) for the axially and / or radially fixed self-supporting position inserts (12). c) Automotive industry.

Description

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  The invention relates to a device for manufacturing lightweight metal pistons for internal combustion engines, in particular for diesel engines, comprising in the region of the bottom of the piston of the piston skirt and / or the bosses of the piston, patches to be sealed by pressure casting, in which the melt introduced into the molding tool is brought to the

solidification under high pressure.

  In the construction of diesel engines, the current advances, such as increased ignition pressures and thermal insulation of the combustion chamber, have more than significant implications for piston technology. The load-bearing ability of the constituent materials of the pistons is increased in addition to fabrication measurements and new materials having a lower thermal conductivity are used. The die-casting process, in which the casting mold is filled with a melt under an adjustable pressure and then brought to solidification under a high pressure of more than 1000 bar, offers the possibility of necessary level the resistance of aluminum alloys, silicon and magnesium which are used, in general, for the manufacture of pistons. Die casting is a great match

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  the manufacture of fibrous composite materials because, because of the large casting pressure, the melt can

  penetrate relatively easily into the fibrous molded body.

  The final pressure of more than 1000 bar places the melt and the fibers at an atomic distance, which can give rise to a controlled reaction which is necessary for a good bond between fibers and melt. But it has been found that inserts, to be selectively sealed in the piston, for example fibrous moldings, sand cores capable of being removed, salt or graphite foam or the like to be removed, are difficult to seal. by casting because the inserts, introduced into the impression of the molding tool, can not be put in position in a safe manner and without being damaged, so that when filling the molding tool of the melt, the patches may float or sink into the melt and / or damage

  may occur during pressurization.

  DE-C-12 50 605 and DE-C-38 07 986 disclose, of course, devices for fixing cores compressed in sand or salt to parts of cores which are intended to cast pistons of internal combustion engines, or regulating elements to be sealed by casting into the pistons. But these devices can not be used when implementing the die casting process. The present invention therefore aims at constituting a device for manufacturing lightweight metal pistons for internal combustion engines, in particular for diesel engines, with patches which must be selectively sealed there by pressure casting so that the inserts can be held in position in the molding tool, in a safe and damage-free manner and so as to eliminate any change in the radial position

and / or axial in the melt.

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  The device according to the invention is characterized by bearing elements which are arranged in the impression of the molding tool for the setting in self-supporting position

  axially and / or radially fixed inserts.

  These bearing elements are, according to one embodiment of the invention, wire spring elements or ribbon spring elements which, according to another characteristic of the invention, are attached to the molding tool , the ends of the spring elements being advantageously introduced into corresponding recesses of the molding tool. The spring elements can also be fixed to casting elements connected to

the molding tool.

  For pistons having in regions of segments, preferably in the region of the first segment groove, an annular support of a special austenitic cast iron or of a fibrous molded body, cast-sealing and connected to the molding tool, it is advantageous to fix the inserts attached to the annular support by spring elements, for the setting self-supporting position, the ends of the spring elements being advantageously introduced into corresponding recesses of the annular support. The invention can be used in particular in light metal pistons in which a ring core made of sand, salt or foam graphite, which can be eliminated and which serves to form a casting ring, must be pour-sealed at the first groove of segments. a cavity forming

cooling channel.

  It is also possible to provide, as a bearing element, on the movable half of the molding tool, axial position holding appendices of the insert, preferably of the core used to form a cooling channel cavity, which are provided on the side of the piston head and which are in the form of pins, which prevent the

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  insert to float in the melt or which, when using an elastic member, push back the insert in the elbows of this elastic member. In the cavities formed in the piston cast by the appendages in the form of pins, it is advantageous to provide the bores for the supply and discharge of the cooling fluid to

  the cavity forming the cooling channel.

  This measurement is particularly suitable for the manufacture of a light metal piston to be cast, preferably while the bottom of the piston is downwards and having a fibrous molded body introduced into the molding tool and forming the piston head or the piston. edge of the bowl forming the combustion chamber in the piston head, an annular support connected to the molding tool and sealing by casting in the region of the zone of the segments, preferably in the region of the first groove segments and a casting core at the first groove of segments, placed on the ring-shaped fibrous molded body, sand, salt or foam graphite to form a cavity forming a cooling channel and which can be removed from the cast piston, this core being pushed into an annular molding of

fibrous molded body.

  The invention is represented by way of example in the drawing and is explained in a more precise manner in this

following.

  Figure 1 is a side elevational view of a wire spring member (1) having two elbows (2, 3) into which a water-soluble salt core (4) is inserted as an insert; and intended to obtain the annular cavity forming a cooling channel in the piston in the region posterior to the first groove of segments. In the section of Figure 2 of a molding tool (5, 6) full of melt, the spring element or spring wire (1) is mounted with the salt core (4).

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  to which it is connected so that the free ends of the elastic wire element (1) are hooked into holes in the annular support (7) special austenitic cast iron. Thanks to this, the salt core (4) is maintained without damage and in a safe manner when pouring and when the melt is pressurized

  in the impression (8) of the molding tool (5, 6).

  Figure 3 is a sectional view of a molding tool (9, 10) filled with the melt. On the bottom of the fixed mold half (9) is the fibrous molded body (11) on which the salt core (12), which can be removed and which is to be sealed by casting into the light metal piston, in the region behind the first groove of segments which is to be introduced into the annular support (16) is placed in a annular molding (13) suitably shaped and preventing any change in the radial position of the salt core (12). The nipple-shaped appendages (14, 15) formed on the upper and movable half (10) of the mold, push the salt core back onto the fibrous molded body (11) and prevent it from floating out. The recesses formed by the appendages Pins (14, 15) on the inner side of the cast piston (17) serve to provide the bores for the supply and discharge of the cooling medium to the channel-forming cavity

cooling.

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Claims (10)

  1. Apparatus for manufacturing lightweight metal pistons for internal combustion engines, in particular for diesel engines, comprising in the region of the bottom of the piston, the skirt of the piston and / or the bosses of the piston, inserts to seal by die-casting, wherein the melt introduced into the mold tool is brought to solidification under high pressure, characterized by bearing elements (1, 14, 15) which are arranged in the cavity (8, 17) of the molding tool (5, 6, 9, 10) for axially freestanding   and / or radially fixed inserts (4, 12).   2. Device according to claim 1, characterized in that the bearing elements consist of elastic elements or spring elements made of wire or ribbon, provided with bent portions (2, 3) of   receiving the patches (4).   3. Device according to claim 2, characterized in that the elastic elements (1) are fixed to the molding tool (5, 6).   4. Device according to claim 2, characterized in that the elastic elements (1) are fixed   cast parts (7) connected to the molding tool.   5. Device according to claim 3 or 4, characterized in that the ends of the elastic elements T 2652526   (1) are inserted in recesses of conjugate shapes of the molding tool (5, 6) or connected castings (7) to the molding tool.   6. Device according to claim 4 or 5, characterized in that, in order to manufacture a lightweight metal piston having, in the region of the zone of the segments, preferably in the region of the first segment groove, an annular support (7 ) of austenitic special cast iron or of a fibrous molded body, to be sealed by casting and molded, the inserts (4) are fixed to the annular support by self-supporting elastic members (1). 7. Device according to claim 6, characterized in that the insert (4, 12) consists of a core of sand, salt or graphite foam that can be removed from the light cast metal piston and used to constitute a cavity forming a cooling channel.   8. Device according to one of claims 1 to   7, characterized in that there is provided, as a support element, on the movable half (10) of the molding tool axially positioning appendages (14, 15) in the axial direction of the insert (4). 12), preferably of the core for forming a cooling channel cavity, which are provided on the side of the piston head and which are in the form of nipples.   9. Use of the device according to claim 8 for producing a lightweight metal piston to be cast, preferably while the bottom of the piston is downward and having a fibrous body (11) introduced into the molding tool (9, 10). ) and forming the piston head or the edge of the bowl forming the combustion chamber in the piston head, an annular support (16) connected to the casting tool and sealing by casting in the region of the segment area , preferably in the region of the first throat 8 ^ 2652526   of segments, and a casting core (12) at the first ring groove on the ring-shaped fibrous body, of sand, salt or foam graphite, which serves to form a channel forming cavity. cooling and can be removed from the cast piston. 10. Use of the device according to claim 8, characterized in that the core (12) is pushed into an annular molding (13) of the molded body fibrous (11).