JP2505229B2 - How to hold a collapsible storage core - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a collapsible core which contributes to forming a bridge portion of a water jacket on a deck when casting a cylinder block. Extremely stable at a predetermined position in the notch provided in the mold wall of
And, it relates to a method of surely holding.

(Prior Art) As a conventional core retaining method of this type for forming a bridge portion of a water jacket on a deck, there is one disclosed in, for example, Japanese Patent Laid-Open No. 232654/1984.

This is because the bridge portion 5 of the water jacket 4 surrounding the cylinder liner 3 is formed on the deck 2 at a predetermined interval in the plan view of the cylinder block 1 shown in FIG. As shown, an intermediate mold 8 composed of left and right mold halves 8a and 8b which can be freely opened and closed is disposed between the fixed lower mold 6 and the movable upper mold 7, and each of these molds 6,7.8
And the cylinder liner 3 into a cavity 9 that is attached to the movable upper die 7 to form a water jacket 4
The jacket mold 10 that contributes to the formation of the bridge mold 5 is projected downward, and the jacket mold 10 has a predetermined circumferential position for forming the bridge portion 5 as shown in FIG. The sand core 12 is fitted into the notch 11 provided in the, and the gap 13 corresponding to the required thickness of the bridge portion 5 is left in the sand core 12 and the upper edge of the notch 11. I am trying.

(Problems to be solved by the invention) However, in such a conventional technique, the sand core 12 is held in the notch 11 of the jacket mold 10 only by frictional engagement between the two. Moreover, since the sand core 12 is provided with a draft for smooth extraction of the jacket mold 10, all the sand cores 12 are placed at their respective predetermined positions in the notches 11. There was a problem that it was very difficult to maintain always and surely.

The present invention has been made by paying attention to such problems of the prior art, and is capable of always holding properly a collapsible core made of sand or the like in a notch of a mold wall portion. The present invention provides a method of holding a storage core.

(Means for Solving Problems) A method for holding a collapsible insert core according to the present invention is provided with a notch in a mold wall portion for forming a water jacket of a cylinder block, and the notch is provided above the notch. Part of the collapsible core is fitted to leave a predetermined space for forming a bridge portion that closes the upper part of the water jacket, and the fitted collapsible core is fitted to both side surfaces of the notch and the collapsible core. Between the gas passage and the gas passage at the opening by reducing the pressure inside the gas passage having the opening on the side surface of the notch disposed inside the mold wall portion due to the frictional engagement force generated between the gas passage and the gas passage. By the synergistic action with the suction force generated between the child and the child, the child is stably held at a predetermined position in the notch.

(Operation) According to this holding method, the collapsible core fitted to the mold wall is restrained from falling off due to the frictional engagement force between the collapsible core and the mold. By suction, relative displacement with respect to the mold is effectively prevented.Therefore, the synergistic effect of the friction engagement force and the vacuum suction force causes the collapsible insert core to move to a predetermined position within the notch of the mold wall. Can be securely held.

In addition, here, when the vacuum suction of the collapsible core was continued until the end of the pouring, the gas passage formed inside the mold wall portion was used as a gas release passage accompanied by positive degassing. Can also function and sufficiently prevent the occurrence of casting defects.

Furthermore, on the other hand, when the gas passage is made to act as a compressed air supply passage under the action of a switching valve or the like, it is left behind in the cast product by the ejection of compressed air from there after the end of casting. The fitting portion of the collapsible insert core, to be precise, the contact surface of the mold with the insert core can be sufficiently cleaned.

(Example) Hereinafter, the present invention will be described based on illustrated examples.

FIG. 1 is a bottom perspective view showing a mold, in which 21 is a mold contributing to the formation of a water jacket and 22 is a mold 21.
The mold holders fixed by bolts or the like or integrally formed are shown in FIG.

The mold 21 here is composed of four continuous mold wall portions 23 each having a substantially cylindrical shape continuous through three constricted portions, and the center portion of each mold wall portion 23 is A liner holder 25 for fitting a cylinder liner 24 indicated by an imaginary line to the mold wall portion 23 projects higher than the mold wall portion 23.

Here, each die wall portion 23 is provided with a notch 26 penetrating in the up-down direction at a predetermined interval, in other words, a notch portion extending in the axial direction, and each notch 26 At the lower end thereof with a length corresponding to the required thickness of the bridge portion described above.

Further, here, with respect to each such notch 26 of the mold wall portion 23, a shape corresponding to the cross-sectional shape of the notch 26, which is curved in an arcuate shape in the figure, is formed with a “<” shape at both end portions. The collapsible insert core (28) having a die engaging portion (27) protruding like a ring is securely and tightly fitted to the position where the notch (26) is narrowed. Here, the notch 26 and the collapsible insert core 28 allow the mold 21 to be smoothly removed after the end of the casting while the collapsible insert core 28 remains inside the casting. For,
It has a draft that gradually narrows downward.

Further, the mold wall portion 23 is provided with a gas passage 29 formed therein and opening on at least one side surface of the notch 26, and each of these gas passages 29 is directly or via a switching valve. Connect to a vacuum pump or other vacuum source.

FIG. 2 is a cross-sectional view showing an example of application of the die 21 as described above to a casting die, which shows a gas passage opened in the notch 26.
29 through the switching valve 30 to a pressure reducing source 31 and a pressurized air supply source.
Connected to each of the 32.

In the figure, 33 is a fixed lower mold, 34 is a movable upper mold to which the mold 21 is attached, and 35 is an intermediate mold. The intermediate mold 35 is a left and right mold half 35a that can be opened and closed. , 35b.

Here, in the present invention, each notch of the mold wall 23
Under the condition that the collapsible insert core 28 is fitted properly into the inside of 26, as shown in FIG. 1, by connecting the decompression source 31 to the gas passage 29 by the action of the switching valve 30, each collapse The decompression suction force is applied to the sex insertion core 28, and the action of the suction force is
The mold closing is completed as shown in FIG. 2, and the runner 36
Until the filling of the molten metal into the cavity 37 is completed, more preferably until the molten metal solidifies.

As a result, the collapsible core 28 receives the reduced pressure suction force from the opening formed on at least one side surface of the notch 26 in addition to the frictional force between the collapsible core 28 and the notch wall surface, and at a predetermined position, It will be sucked and held sufficiently accurately and a casting with the desired shape and dimensions, here a cylinder block, will always and reliably be cast, the deck of which is shown in FIG. Similarly to the case shown, a bridge portion having an appropriate thickness that can sufficiently effectively contribute to increasing the rigidity of the cylinder block is formed.

Here, when the above-described vacuum suction is continued until the pouring is completed, the generated gas from the binder, water, etc. contained in the collapsible insert core 28 is extremely effectively out of the mold. Since it is discharged, the casting defects caused by the generated gas can be almost completely removed.

Then, after the casting is completed in this way, by raising the movable upper mold 34, the mold 21 comes out upward while leaving each of the collapsible cores 28 left in the cylinder block, respectively. The mold wall portion 23 forms a water jacket opening in the deck.

Therefore, thereafter, by switching the switching valve 30, the gas passage 29 is connected to the pressurized air supply source 32, thereby ejecting pressurized air from the side surface opening of the notch 26 and adhering to the notched side surface. The residue of the collapsible storage core 28 can be sufficiently removed.

Therefore, here, the collapsible core 28 fitted in the notch 26 of the mold wall 23 is provided with a gas passage 29 that opens in the notch 26.
By sucking and holding the collapsible insert core 28 in the notch via the, it is possible to position the collapsible insert core 28 at a predetermined position in the notch with sufficient accuracy, and as a result, the cylinder block as intended is always ensured. Will be manufactured.

(Effects of the Invention) Thus, according to the present invention, the collapsible insert core fitted in the notch through the gas passage formed in the mold wall portion and opening at the side surface of the notch provided therein. By sucking, the synergistic action of this suction force and the frictional engagement force generated between both side surfaces of the notch and the collapsible core allows the collapsible core to be accurately held at a predetermined position in the notch. And a cylinder block having the desired shape and dimensions can always be reliably manufactured.

[Brief description of drawings]

FIG. 1 is a bottom perspective view illustrating a mold structure used for carrying out the present invention, FIG. 2 is a cross-sectional view illustrating a casting example by the method of the present invention, FIG. 3 is a plan view illustrating a cast product, and FIG. Is a cross-sectional view illustrating a conventional casting mold, and FIG. 5 is a view illustrating a conventional method. 21 …… Mold, 23 …… Mold wall 25 …… Liner holder, 26 …… Notch 27 …… Mold engaging part, 28 …… Collapsible insert core 29 …… Gas passage, 30 …… Switching valve 31 ...... Decompression source

Claims (1)

(57) [Claims] 1. A notch is provided in a mold wall portion for forming a water jacket of a cylinder block, and a predetermined space for forming a bridge portion for closing the upper portion of the water jacket is left in an upper portion of the notch. The collapsible core is fitted with the collapsible core, and the fitted collapsible core is placed inside the mold wall part due to the frictional engagement force generated between the side surfaces of the notch and the collapsible core. A depressurized atmosphere is created in the gas passage having an opening on the side surface of the notch, and a predetermined position in the notch is created by the synergistic action of the suction force generated between the gas passage and the collapsible core at the opening. A method for holding a collapsible insert core, which is characterized in that it is stably held at