JPH051084B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a stalk for low-pressure casting, and more specifically to a method for controlling pouring speed to improve the function of preventing poor metal circulation and entrainment of metal oxide coatings. This invention relates to a low-pressure casting stalk formed by fitting and supporting members.

Background Art A low-pressure casting device, as disclosed in JP-A-58-65562, for example, injects molten metal stored in a heat-retaining furnace, such as a crucible, into a mold through a stalk and a supplyer. is configured to do so. In such low-pressure casting equipment, a film of slag and metal oxides adheres to the inner surface of the stalk over time, so when performing periodic maintenance work, it is necessary to use an appropriate crushing device such as a pneumatic hammer. The deposits are crushed and taken out of the system.

In addition, the known stalk maintains a relatively low flow rate of the molten metal supplied into the mold through the stalk and the supplyer to prevent air bubbles from being drawn into the inside of the casting. Dimensions including diameter have been adjusted to allow for flow. FIG. 2 is a vertical cross-sectional view of a conventional stalk, in which a lower mold 2 is connected to the upper end of the stalk body 1, and the inner diameter of the pouring spout of the lower mold 2 is the same as that of the stalk body 1. It is designed to have approximately the same diameter as the inner diameter of.

On the other hand, a heat insulating material 3 is attached to main parts of the inner wall surfaces of the stalk body 1 and the lower mold 2 by known joining means such as fitting or coating.

Problems to be Solved by the Invention In the conventional low-pressure casting equipment as described above, when trying to remove hardened slag or metal oxide coatings that have adhered to the inner surface of the stalk, the stalk is crushed by the crushing device. There are many cases where the casting equipment itself is damaged, and there are restrictions on the size of low-pressure casting equipment in order to extend its service life and reduce installation investment costs. Also,
If the diameter of the stalk is increased in an attempt to reduce the flow rate of molten metal into the mold sprue, it becomes difficult to control the low-pressure air flow that is the medium for sending the molten metal, resulting in poor molten metal circulation and metal leakage inside the casting. Problems such as the inflow of oxide film or the contamination of slag occur, and the quality of the cast product deteriorates.

The main object of the present invention is to provide conventional low pressure casting equipment;
In particular, it is an object of the present invention to provide a stalk for low-pressure casting that has novel structural characteristics that can solve the above-mentioned problems found in stalks.

Means for Solving the Problems In view of the above object, the present invention provides a stalk body having a hollow cylindrical shape, and a pouring speed control device made of a heat insulating material that is detachably fitted and supported on the upper end of the stalk body. The pouring speed control member is essentially a stalk for low-pressure casting, which has a molten metal inlet having a diameter smaller than the inner diameter of the stalk body opened on the inner surface of the upper end of the stalk body. be.

Effect By opening the molten metal inlet in the pouring speed control member with a diameter smaller than the inner diameter of the stalk body,
The passage speed of the molten metal at the molten metal inlet can be adjusted appropriately according to the dimensions of the cast product, and molten metal supply conditions suitable for preventing air entrainment and mixing of metal oxide films are ensured.

Embodiment FIG. 1 is a longitudinal cross-sectional view illustrating a low-pressure casting stalk according to the present invention. , low pressure casting stoke 1
As shown in the figure, the stalk body 11 is a hollow cylindrical cast iron type, and the stalk body 11 is removably fitted and supported on the upper end of the stalk body through a suitable fixing means such as fitting or temporary adhesion. It consists of a pouring rate control member 12 made of a ceramic heat insulating material.

The pouring speed control member 12 has a molten metal inlet 13 with a diameter d, which is smaller than the inner diameter D of the stalk body, opened on the inner surface of the upper end of the stalk body 11, and a molten metal inlet 13 having a diameter d, which is smaller than the inner diameter D of the stalk body. 1
A molten metal reservoir 15 is formed whose diameter gradually increases toward the upper end opening 14 of the molten metal.

The pouring speed control member 12 has its body 16 fitted into a step 17 formed on the inner wall surface of the stalk body 11, and has a lid 18 attached to its upper end. It is integrally connected to the stalk body 11 by screwing to a flange 19 formed at the upper end of the stalk. The low-pressure casting stalk 10 having such a structure is connected to a molten metal storage body, for example, a crucible made of black smoke, and a casting mold (none of which are shown) in a conventional manner to constitute a low-pressure casting device. do.

When attempting to supply molten metal in the molten metal reservoir body, for example, molten aluminum, to the inside of the mold using the low-pressure casting stalk 10 according to the present invention,
A diameter d smaller than the inner diameter D of the stalk body 11
The molten aluminum passing through the molten metal inlet 13 is throttled by the molten metal inlet 13 to temporarily increase the flow velocity. On the other hand, the flow velocity distribution of the molten aluminum inside the stalk body 11 is as follows.
Due to the resistance with the inner wall surface of No. 1, the speed on the inner wall surface side becomes low, and the axial center of the flow path becomes high speed. This flow velocity difference is
This is further promoted by narrowing the opening area of the molten metal inlet 13 into an orifice shape, and the slag and metal oxide coatings are crushed and automatically moved toward the inner wall surface of the stalk body 11 due to the above-mentioned flow velocity difference. Therefore, the molten aluminum passes through the molten metal inlet 13 and flows into the molten metal reservoir 15 with the slag and metal oxide coating removed. Since the diameter of the molten metal pool 15 gradually increases toward the upper end opening 14 of the stalk body 11, the molten aluminum that is once accelerated when passing through the molten metal inlet 13 is gradually decelerated after flowing into the molten metal pool 15. , it flows into the mold while maintaining a stable flow state without entrainment of bubbles.

Effects of the Invention As can be understood from the above explanation, by using the low-pressure casting stalk according to the present invention, it is possible to effectively prevent the inflow of slag and metal oxides or the entrainment of air bubbles into the inside of the cast product. I can do it.
Further, by adjusting the diameters of the molten metal inlet and the molten metal reservoir according to the dimensions of the cast product, the molten metal can obtain a flow velocity distribution suitable for preventing clogging in the upper part of the stalk. Therefore, according to the present invention, regarding improvement of quality of cast products and improvement of castability,
Remarkable effects are achieved that are significantly superior to conventional low-pressure casting stalks. Furthermore, since the pouring rate control member can be easily removed from the stalk body by loosening the tightening screw and removing the lid, replacement work can be easily carried out in the event of damage. In this way, the present invention not only improves the quality of connected products, but also
This can also greatly contribute to improving the productivity of low-pressure casting processes.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view illustrating a low-pressure casting stalk according to the present invention, and FIG. 2 is a vertical cross-sectional view of a conventional stalk. 10... Stoke for low pressure casting, 11... Stoke body, 12... Molten metal pouring speed control member, 13... Molten metal inlet, 14... Upper end opening of stalk body,
15... Molten metal pool, D... Inner diameter of stalk body,
d...Inner diameter of molten metal inlet.

Claims (1)

[Claims] 1 Consists of a hollow cylindrical stalk body and a pouring speed control member made of a heat insulating material that is detachably fitted and supported on the upper end of the stalk body, and the pouring speed control member is attached to the upper end of the stalk body. A stalk for low-pressure casting characterized by having a molten metal inlet opening on the inner surface thereof having a diameter smaller than the inner diameter of the stalk body.