DE1550043A1 - Light metal piston with expansion-regulating inserts and casting mold used for its production - Google Patents

Description

MAHLE Komm.-Ges., Stuttgart-Bad.Cannstatt, Pragstr. 26-46

Light alloy pistons with expansion regulating Deposits and casting mold used for its manufacture

The invention relates to a light metal piston with a Shank whose radial thermal expansion is parallel to the Longitudinal piston axis and essentially transverse to the piston pin axis running strip inserts made of a material with lower coefficient of thermal expansion than that of the piston material it is regulated. It also relates to a casting mold used to produce such a piston.

In the known piston of the type described the strain regulating Streifeneinlageh have no special holding means mi "with which they can be held in dor mold during casting. Rather, the deposits only have those parts that contribute directly to the regulation of the debris. Retaining means provided on the casting mold, for example retaining pins or magnetic mountings engaging in loops in the inserts, must therefore attack the stretch-regulating parts. As a result, one is bound to a certain extent in the design and arrangement of the strip inserts and, to a large extent, in the design of the casting mold. The plane directed towards the piston pin axo must be the plane of separation of the mold parts of the latter that can be lifted off from one another

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has been chosen »in dar dia piston lttncoaxo read, because aonai the strip inlays cannot be easily inserted into the ceüffnoto form. This type of Formtclluris makes mass production more difficult, because it enables the arrangement of hollow spaces connected to a common inflow channel in a casting mold.

According to the invention, in a piston of the type described at the outset, the elongation-regulating strip inserts are connected with insert parts running transversely to the longitudinal axis of the piston, which extend in the ring zone or in the parts of the piston initially located in this area to the outer contour of the piston. These insert parts can be used as holding means for the stretch-regulating strip inserts in the casting mold and enable a mold division perpendicular to the longitudinal axis of the piston and thus the arrangement of more than two mold cavities with a common, centrally located pouring channel. ·

If only this goal is to be achieved, then one can the insert parts running transversely to the longitudinal axis of the piston as integrally connected to the strain-regulating insert parts more or less narrow tongues. In many cases, however, it will be advantageous to use the crosswise to the Kolbonlängsaxe extending deposit parts to give the shape of hangings or ring segments, welohe in a known manner Separate the shaft parts from the piston head that are under the action of the stretch-regulating strip inserts, thereby creating a allow unaffected by the thermal expansion of the latter control of the thermal expansion of the piston skirt. So far a one-piece connection is not possible, recommends it is, the stretch-regulating strip inserts with the ring or ring segment-shaped inserts by welding connect to. If necessary, transversely arranged ring or ring-shaped insert parts also for the reinforcement of KoI-

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In order to fix the deposits exactly when casting such flasks on eich recommends ensuring that they are in the casting mold furthermore, especially in the case of larger dimensions, than more Holding means on the stretch-regulating strip inserts in Tolle protruding towards the open end of the shaft like this to arrange that these on the finished piston over the pin hubs protrude. Close to the finishing of the colons these parts Jo completely or partially removed as required * ζ 5. be ground off, in order to bring all pistons of a series to the same weight. Too easy failed pistons can possibly stick to these outstanding Parts also small pieces of iron are attached.

Two embodiments of an example of a piston according to the invention, as well as an exemplary embodiment for the production of such Casting molds used for pistons are shown in the drawings.

Pig. 1 shows a longitudinal section in the direction of the bolt axis Embodiment of a piston in which the transverse to the KoI benlttngsaxe running insert parts through with the stretch-regulating Strip inlays connected in one piece. Tongues formed are.

Fig. 2 shows a partial longitudinal section of this piston transversely to the bolt ax,

Fig. 3 is a cross section along the line III-IiI- of Fig, l, and

Fig. K shows a cross section along the line IV-IV of Fig.l.

Fig. 5 shows a partial longitudinal section through an embodiment, in which the transverse to the piston longitudinal axis

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Insert parts have the shape of hanging segments, and

Flg. 6 shows a cross section near the line VZ-VX in FIG Fig. 5 shows *

Fig. 7 shows a further embodiment in partial longitudinal; cut in the direction of the bolt axis, in the case of the insert part running transversely to the longitudinal axis of the piston in a closed Ring is provided. ·

Fig. 8 is a cross section taken on the line VIII-VZIZ in Fig. 8 Fig. 7, while

Flg. 9 a longitudinal section near the line ZX-IX in Fig. 8 and:

Flg. 10 shows a cross-section near the line X-X in FIG. 4th

Flg. 11 shows the lower part echematically in plan view a casting mold with Seohs mold cavities for casting pistons according to FIGS. 1 to 4

Fig. 12 shows on a larger scale and in more detail " an excerpt from Flg. Il dar

13 is a longitudinal section along the line XZZZ-XZZX in Fig. 12 and

14 shows a longitudinal section on a smaller scale the line XIV-XZV in Fig. 11.

At the execution desk near the Flg. 1 to 4 consists of The light metal body of the piston consists of a head with the base 11 and the ring zone 12, as well as from the shaft 13 which encompasses only two "sliding shoes" and extends through the ring zone Cross slots 14 separated 1st, and from the bolt hubs 15,

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those with the piston head 11 duroh StUterlppen 16 and with the shaft 13 are connected by transverse ribs 17. To regulate the radial thermal expansion of the piston shaft 13 are in known catfish strip inserts 21 made of sheet steel or the like arranged "the aioh here on the transverse ribs. 17 put on and together with these form pear-shaped connecting links. These strip inserts 21 are anchored in the bolt hubs 15 and at their ends in the Sohaft 13 * In the area of the pin bosses 15, they point in the direction the open end of the shaft protruding parts 22 .'- on "the to Purpose of weight compensation completely or partially removed can be. They are also tongue-like with them. Parts, 23 integrally connected »which in the lower annular groove the ring zone 12 extend to the bottom of the groove. ·

In the embodiment according to Flg. 5 and 6 and with the stretch-regulating strip inserts, ring segment-shaped inserts .. » layer parts 23 * connected, which form the load-bearing shaft part from the ring zone 12, so that the arrangement of transverse slots unnecessary »<

The ring-shaped insert parts 23 ″ provided in the exemplary embodiment according to FIGS. 7 to 10 have the same effect.

In the case of pistons that have not yet been finished, they are positioned across insert parts 23 * 23 'or 23 "beyond the outer contour of the piston, since it Yes according to the invention for retaining the inserts in the mold should serve. This can be seen from Figs. 12 and 13 / the one mold with inlaid inlays «own.

Each casting mold consists of a lower part 31 and an upper part 32 which can be lifted off therefrom, which is great between • enclose in a mold cavity 33. Also belongs to everyone

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Form a core 34 determining the internal shape of the piston and a quill 35 serving to form the bolt holes. The plane of separation between the two barrel parts 51 and 32 runs in the plane in which the insert parts 23, which are directed transversely to the longitudinal axis of the piston, are for the protruding parts of the latter 31 embeddings J6 are provided in the molded part. Furthermore, recesses 37 for receiving the parts 22 of the inserts 21 are provided in the core 34. The recesses 36 and 37 into which the inserts can easily be inserted when the mold is open, their position within the mold cavity is so well secured that they retain their position when using any of the known casting processes *

As can be seen from FIGS. 11 and 14, several, for example six, mold cavities 33 can be arranged around a central pouring channel with a corresponding number of branches 38 and risers 39. _4th

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Claims (6)

Claims 1. Light metal piston with a shaft, the radial thermal expansion of which is regulated duroh parallel to the longitudinal axis of the piston and essentially transverse to the longitudinal axis of the piston and made of a material with a smaller WUrraeausdehnungsbeiwort than that of the piston material, characterized in that the expansion-regulating strip inserts (21) with transverse to the longitudinal axis of the piston Insert parts (23, 2J ¹ , 22 ") are connected, which extend in the ring zone or in the parts of the piston skirt which are closest to it as far as the outer contour of the piston. 2 «light metal piston according to claim 1, characterized in that the insert parts extending transversely to the longitudinal axis of the piston de form of tongues (2}) connected in one piece with the stretch-regulating strip inserts. 3. Light metal pistons naoh claim 1, characterized in that that the insert parts running transversely to the longitudinal axis of the piston have the shape of rings (22 *) or ring segments (22 ') 4. Light metal piston naoh claim 3 »characterized in that that the stretch-regulating strip inserts (21) with the ring-shaped or ring-shaped insert parts (2J "or 2> ') duroh welding are connected. 5. For the production of pistons according to claims 1 to 4 serving mold with two liftable mold parts, characterized in that the parting plane between the two Fon parts perpendicular to the longitudinal axis of the mold cavity or of the piston runs in the plane in which the transverse to the piston longitudinal axis extending insert part · lie, and 9G9881 / Q65A - 2 - BATH that serving to accommodate these parts recesses (26)
are provided in the parting line. 6. Casting mold according to Anspruoh 5 » characterized in that further recesses (27) for receiving on the finished piston over the pin bosses in the direction of the open shaft end protruding parts (22) of the elongation-regulating strip inserts on the determining the inner shape of the piston
Core (24) are provided. 09881/0654