Die casting mold for casting cylinder crankcases or crankcase subparts

Abstract

Die casting molds for casting cylinder crankcases or crankcase subparts having a stationary molded part (10), in which, at least partially, a sprue system (26) for distributing the melt is formed, and movable molded parts (28, 29), in which, at least partially, a cavity (20) for forming a cylinder crankcase (34) or a crankcase subpart is formed, are known. In order to improve the microstructures,according to the invention, between the stationary molded part (10) and the movable molded parts (28, 29), an intermediate molded part (14) is arranged, which at least partially delimits the cavity (20) for forming the cylinder crankcase (34) or the crankcase subpart, and in which, at least partially, the sprue system (26) and a plurality of gates (22) are formed, which terminate in thick-walled areas (42) of the cylinder crankcase (34) or the crankcase subpart.

Description

[0001] The invention relates to a die casting mold for casting cylinder crankcases or crankcase lower parts, comprising a stationary mold part in which a sprue system for distributing the melt is formed at least partially, and movable mold parts in which a cavity for forming a cylinder crankcase or a crankcase lower part is formed at least partially.

[0002] Die casting molds for the production of cylinder crankcases or crankcase lower sections, also called bedplates, are well known, with the die casting process being used primarily in the field of light metal casting, especially aluminum alloys or magnesium alloys. The molds used usually have a one- or two-sided gate onto the oil pan flanges or the parting surfaces between the cylinder crankcase and the crankcase lower section. However, this has the consequence that a sufficiently low-porosity structure is often not achieved in the thick-walled areas during casting, as the required pressure often cannot be applied via the gate because the thinner areas in between solidify earlier. For this reason, additional squeezers are used below the bearing blocks in order to generate a sufficiently high holding pressure in the thick-walled areas.

[0003] In order to improve the microstructures achievable with these casting processes, DE 10 2006 030 129 B4 proposes a low-pressure casting process in which casting is carried out in a horizontal position and the feeding takes place directly via the bearing block, so that a holding pressure can also be generated at this gate.

[0004] The disadvantage of this design, however, is that the bearing block area can only be filled from one side, so structural differences within the bearing block area cannot be ruled out. Furthermore, due to the relatively large blast area, re-pressing at higher pressures is not possible.

[0005] Furthermore, from DE 10 2013 105 769 A1 a die casting mold with fixed and movable mold parts is known, in which a sprue system is formed in a movable mold part, the gates of which extend through an intermediate mold part into a cavity of a cylinder crankcase to be cast on the cylinder walls.

[0006] Furthermore, from DE 10 2012 107 363 A1 a three-plate tool for casting an engine mount is known, in which the sprue system is formed in one of the mold parts, several conical gates and the cavity are formed in a second mold part and the third mold part delimits the cavity in the opposite direction.

[0007] The challenge, therefore, is to provide a die-casting mold for casting cylinder crankcases or crankcase lower sections that can achieve a good microstructure in thick-walled areas of the castings without the need for additional squeezers. In addition, the possible holding pressure should be increased compared to existing designs and handling during post-processing should be simplified.

[0008] This object is achieved by a die-casting mold for casting cylinder crankcases or crankcase lower parts having the features of claim 1.

[0009] By arranging an intermediate mold part between the stationary mold part and the movable mold parts, which at least partially defines the cavity for forming the cylinder crankcase or the crankcase lower section and in which the sprue system and several gates are at least partially formed, which open at the thick-walled regions of the cylinder crankcase or the crankcase lower section, wherein the gates are designed in a funnel shape and narrow towards the cavity, it is achieved that the thick-walled regions can be supplied directly with melt and the holding pressure can be introduced via the thick-walled regions, so that the regions to solidify last can be supplied with melt throughout the entire solidification time. This connection compensates for shrinkage deficits during the solidification process, thus achieving a low-porosity structure even in these regions.The funnel shape of the gates simplifies demolding and creates predetermined breaking points at the transition between the cavity or the casting and the runner system, ensuring a clean separation of the casting from the runner system when the mold is opened. This also improves the conditions for subsequent aging, quenching, and heat treatment, as the runner system is no longer present and therefore no energy can be drawn from it.

[0010] Preferably, a first parting plane is formed between the stationary mold part and the intermediate mold part, and a second parting plane is formed between the intermediate mold part and the movable side mold parts. These two parting planes are arranged essentially parallel to a base surface of the cylinder crankcase or crankcase lower section to be cast. This enables easy demolding with a clean separation of the casting from the sprue. This allows for multiple gates to be created for a single cavity, particularly in difficult-to-access positions within the cavity.

[0011] In particular, the sprue can be ejected between the stationary mold part and the intermediate mold part when the mold is opened, and the cylinder crankcase or the crankcase lower section can be ejected between the intermediate mold part and the movable mold parts when the mold is opened. The tool used thus ensures easy separation when the plates are moved apart.

[0012] In an advantageous embodiment, the die-casting mold can be filled from the crankcase side, and the gates open at the bearing block of the cylinder crankcase or the crankcase lower section. This allows the filling to be carried out directly onto the loaded and thick-walled bearing block, thereby achieving a low-porosity structure.

[0013] In an advantageous alternative embodiment, the die-casting mold can be filled from the cylinder deck side, and the gates open in the area of ​​the tie rod cores of the cylinder crankcase, allowing filling below the water jacket core toward the bearing blocks or the tie rod cores. This allows these thick-walled areas to be produced with a low-porosity structure through the internal filling. This achieves a good structure in the area of ​​the loaded tie rods.

[0014] Alternatively, the die-casting mold can preferably be filled from the cylinder cover side and the gates open in the area of ​​the cylinder walls of the cylinder crankcase, so that improved structures are achieved by the increased pressure to be applied.

[0015] Advantageously, two gates are formed on each bearing block, which are arranged on both sides of each bearing shell receptacle of the cylinder crankcase or the crankcase lower part, so that a filling on both sides of the bearing block is produced, which leads to a uniform structure of the bearing block area regardless of the casting layer.

[0016] Preferably, a main pouring runner is formed between the stationary mold part and the intermediate mold part. This main pouring runner extends along the length of the mold parts. From this runner, several individual pouring runners extend perpendicular to the main pouring runner on both sides through the intermediate mold part to the cavity. This design achieves uniform and low-turbulence filling with constant holding pressure. This results in a uniform distribution of the melt and a consistent feeding into the bearing seats.

[0017] Preferably, a projected area of ​​the sprue system arranged in the intermediate mold part onto the second parting plane between the movable mold part and the intermediate mold part is arranged within a projected area of ​​the cavity onto this parting plane. This design reduces the blasting area of ​​the die casting mold, since the sprue system does not have an additional blasting area for the die casting mold. This allows either the holding pressure to be increased or the mold clamping forces to be reduced.

[0018] In a preferred embodiment of the invention, the individual casting runners have a diameter that essentially corresponds to the width of the bearing block. This large diameter allows the holding pressure from the piston system to act for a significantly longer period during the solidification phase.

[0019] The die-casting mold according to the invention is therefore particularly suitable for producing cylinder crankcases and crankcase lower sections with high strength by achieving low-porosity structures in highly stressed, thick-walled areas without the need for additional squeezers. Higher final pressures are possible due to the reduced blast area, and the amount of recycle material is reduced during demolding due to the small sprue system.

[0020] In the following, a die-casting mold according to the invention and its use for producing a cylinder crankcase are explained by way of example with reference to the figures.

[0021] The Figure 1 shows schematically a side view of a die casting mold according to the invention with a crank chamber-side sprue system in the closed state in a sectional view.

[0022] The Figure 2 schematically a side view of the die casting mold according to the invention Figure 1in the opened state in a sectional view.

[0023] The Figure 3 shows schematically the cast cylinder crankcase with the crankcase-side gating system in perspective view.

[0024] The Figure 4 shows schematically a side view of an alternative die casting mold according to the invention with a cylinder cover-side sprue system in the closed state in a sectional view.

[0025] The die casting mold according to the invention shown in the figures has a stationary mold part 10, through which the melt is introduced into the die casting mold. This stationary mold part 10 is attached to a machine plate (not shown), which is connected to a casting chamber and the casting piston for generating pressure, whereby the casting piston forces the melt through the stationary machine plate and into the stationary mold part 10.

[0026] A main casting runner 12 is formed between the stationary mold part 10 and an intermediate mold part 14. Thus, a first parting plane 16 is formed between the intermediate mold part 14 and the stationary mold part 10, at which the two mold parts 10, 14 rest on one another and are pressed together during casting, and at which the two mold parts 10, 14 are separated from one another after casting.

[0027] Extending through the intermediate mold part 14 from the main runner 12, perpendicular to the parting plane 16 and perpendicular to the main runner 12, are eight individual runners 18, arranged in four rows of two pairs each. These individual runners 18 are slightly truncated conical in shape, tapering towards a cavity 20 and having an additional funnel-shaped cross-sectional constriction 24 at their ends, with which they open at the cavity 20 and serve as gates 22 to the casting. The individual runners 18, together with the main runner 12, form a sprue system 26 of the die casting mold, which, thanks to the arrangement of the individual runners 18 relative to the main runner 12, can supply the cavity 20 with melt with low turbulence.

[0028] The cavity 20 is formed between the intermediate mold part 14 and side mold parts 29, which are adjoined by a movable mold part 28. Insertable molds 30 are arranged on the movable mold part 28, which, like the movable mold part 28, are attached to a movable machine plate (not shown). Accordingly, a second parting plane 32 of the die casting mold is formed between the intermediate mold part 14 and the side mold parts 29, which simultaneously forms a base surface of the casting to be cast.

[0029] In the present embodiment, the cavity 20 has the shape of a cylinder crankcase 34 with three cylinders 36, whose inner cylinder walls 38 are formed by the molds 30 used, and whose cylinder deck 39 and the outside of the cylinder crankcase 34 are formed by the movable mold parts 28, 29. A crankcase 40 is delimited by the intermediate mold part 14, with the gates 22 each opening into thick-walled regions 42 of the cylinder crankcase 34, which in the present embodiment are formed by bearing blocks 44 of the cylinder crankcase 34. Tie rod cores 46 extend from the cylinder deck 39 into the cylinder crankcase. Each of the four bearing blocks 44 is fed with melt via a pair of individual pouring runners 18, with the gates 22 being arranged on either side of bearing shell receptacles 48.

[0030] If the die casting mold is now filled with melt, it flows into the cavity 20 via the main pouring runner 12 and the individual pouring runners 18. The melt then begins to solidify in the cavity 20, with thin-walled and cooled regions, such as the cylinders 36, which can be cooled via the molds 30, solidifying faster than the thick-walled regions 42. During solidification, shrinkage of the casting begins, which increases with increasing volume and could normally lead to porous structures or even shrinkage cavities. The die casting mold according to the invention allows for the injection of melt via the gates 22 directly into the thick-walled regions 42 using pressure generated by the casting piston, so that a very low-porosity structure can be achieved even in the thick-walled regions 42.

[0031] In this embodiment, the pressure generated during the die-casting process acts exclusively on a projected area of ​​the cylinder crankcase 34 or the cavity 20 on the second parting plane 32 between the intermediate mold part 14 and the movable side mold parts 29, since the entire casting runner on the intermediate mold part 14 or the projected area of ​​the sprue system 26 within this projected area acts on the base area or the second parting plane 32. Accordingly, a very high holding pressure can be applied or, compared to known embodiments, the closing force on the die-casting mold can be reduced.

[0032] After solidification, the die casting mold is opened at both parting lines. Due to their smallest cross-section, the individual runners 18 break off in the area of ​​the gates 22, so that an entire solidified sprue 50 is ejected between the stationary mold part 10 and the intermediate mold part 14. The cylinder crankcase 34 is ejected via ejector 52 after the molds 30 are withdrawn from the movable mold part 10 and between the movable mold part 10 and the intermediate mold part 14, ensuring a clean separation between the casting and the sprue 50.

[0033] In the Figure 4an alternative possibility for casting a cylinder crankcase 34 is shown. In this case, filling does not take place on the crankcase side, but on the cylinder cover side. In the fixed mold part 10, a part of the sprue system 26 is again formed, which continues in the intermediate mold part 14. This likewise has eight individual runners 18, which extend in a plane between the cylinders 36 to an area in which the tie rod cores 46 are arranged and from there fill the thick-walled area 42. Alternatively, the individual runners could also extend through the parts of the intermediate mold part 14 forming the cylinders 36 and there, from the inside, via the crankcase-side end of the cylinder walls 38, in turn fill the thick-walled areas of the bearing blocks 44.In this embodiment, the cavity 20 is also formed between the intermediate mold part 14, the movable side mold parts 29, and the movable mold part 28, with the mold part 28 forming the crankcase 40 and the side mold parts 29 forming the cylinder outer surfaces and the outer surface of the crankcase 40. The cylinder deck is formed by the intermediate mold part 14. In these embodiments, the pressing and feeding also take place directly onto the thick-walled regions 42 of the cylinder crankcase, which are most subject to shrinkage, so that a low-pore structure can be achieved here as well. The sprue 50 is also separated from the casting by simply opening the die-casting mold.

[0034] Such a die casting mold opens up various possibilities for filling and feeding the relevant thick-walled areas of a casting, and in particular of a cylinder block, so that a low-porosity structure can be achieved. At the same time, this filling and feeding can take place at high pressures, since the small sprue system keeps the mold's burst area very small. However, the cross-sections of the individual runners or the entire sprue system can be made relatively large, allowing the applied holding pressure to act for a long time. This also leads to improved structures in the relevant areas of the bearing block or the tie rods. Since the sprue is also very small, the amount of recycled material is reduced, which can save energy. In addition, the necessary post-processing is reduced, since the sprue automatically detaches from the casting at the correct position when the mold is opened.

[0035] It should be clear that the scope of protection of the application is not limited to the described embodiment. In particular, other castings, especially bedplates for cylinder crankcases, can also be produced in this way.

Claims

1. A die casting mold for casting cylinder crankcases or crankcase sub parts, comprising a stationary molded part (10) in which a sprue system (26) for distributing the melt is at least partially provided, movable molded parts (28, 29) in which a cavity (20) for forming a cylinder crankcase (34) or a crankcase sub part is at least partially provided, characterized in that an intermediate molded part (14) which is arranged between the stationary molded part (10) and the movable molded parts (28, 29) and which at least partially delimits the cavity (20) for forming the cylinder crankcase (34) or the crankcase sub part and in which the sprue system (26) and a plurality of gates (22) which open at thick-walled regions (42) of the cylinder crankcase (34) or the crankcase sub part are at least partially provided, wherein the gates (22) are formed so as to narrow in a funnel-shaped manner with respect to the cavity (20).

2. The die casting mold for casting cylinder crankcases or crankcase sub parts according to claim 1, characterized in that a first parting plane (16) is provided between the stationary molded part (10) and the intermediate molded part (14) and a second parting plane (32) is provided between the intermediate molded part (14) and the movable side molded parts (29), which parting planes are arranged substantially parallel to a base surface (17) of the cylinder crankcase (34) to be cast or of the crankcase sub part to be cast.

3. The die casting mold for casting cylinder crankcases or crankcase sub parts according to claim 1 or 2, characterized in that the sprue (50) can be ejected between the stationary molded part (10) and the intermediate molded part (14) when the die casting mold is opened, and the cylinder crankcase (34) or the crankcase sub part can be ejected between the intermediate molded part (14) and the movable molded parts (28, 29) when the die casting mold is opened.

4. The die casting mold for casting cylinder crankcases or crankcase sub parts according to any one of claims 1 to 3, characterized in that the die casting mold can be filled on the crankcase space side, and the gates (22) open at the bearing block (44) of the cylinder crankcase (34) or of the crankcase sub part.

5. The die casting mold for casting cylinder crankcases or crankcase sub parts according to any one of claims 1 to 3, characterized in that the die casting mold can be filled on the cylinder cover side, and the gates (22) open in the region of the tie rod cores (46) of the cylinder crankcase (34).

6. The die casting mold for casting cylinder crankcases or crankcase sub parts according to any one of claims 1 to 3, characterized in that the die casting mold can be filled on the cylinder cover side, and the gates (22) open in the region of cylinder walls (38) of the cylinder crankcase (34).

7. The die casting mold for casting cylinder crankcases or crankcase sub parts according to claim 4, characterized in that two gates (2) are provided at each bearing block (44), which gates are arranged on both sides of each bearing shell receptacle (48) of the cylinder crankcase (34) or of the crankcase sub part.

8. The die casting mold for casting cylinder crankcases or crankcase sub parts according to any one of the preceding claims, characterized in that a main casting run (12) is provided between the stationary molded part (10) and the intermediate molded part (14), which main casting run extends along the length of the molded parts (10, 14, 28) and from which a plurality of individual casting runs (18) extending perpendicularly to the main casting run (12) extend on both sides through the intermediate molded part (14) to the cavity (20).

9. The die casting mold for casting cylinder crankcases or crankcase sub parts according to any one of the preceding claims, characterized in that a projected area of the sprue system (26) arranged in the intermediate molded part (13) onto the second parting plane (32) is arranged within a projected area of the cavity (20) onto the second parting plane (32).

10. The die casting mold for casting cylinder crankcases or crankcase sub parts according to any one of the preceding claims, characterized in that the individual casting runs (18) have a diameter which substantially corresponds to the width of the bearing block (44).

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