JPH0110132Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Field of Application) The present invention relates to improvement of a mold used for manufacturing sand molds for casting.

(Prior art) For example, when casting an engine cylinder block, etc., a sand mold to be used must be manufactured in advance, but the method for manufacturing this sand mold is as follows.
The so-called cold box method is commonly used (see, for example, Japanese Utility Model Application No. 57-37547). this is,
Sand is injected into a mold, and then the sand is solidified by acting on the sand with a curing gas blown in from the outside, thereby obtaining the desired sand mold. In that case, as shown in Fig. 1, the mold A has a plurality of exhaust passages B communicating between the cavity side and the outside so that the air can escape during the sand injection and the hardening gas can be discharged. ...B is provided. As shown in FIGS. 2 and 3, a pent plug C having a mesh C ₁ stretched over its upper surface for preventing sand leakage is fitted into the cavity side opening of the exhaust passages B...B.

However, in the case of conventional molds as mentioned above,
Since the curing gas is exhausted only from the part where the vent plug C is fitted, the curing gas has poor circulation, and the sand located away from the vent plug C or the exhaust passage B is particularly susceptible to the curing gas. There was a problem of insufficient curing due to insufficient supply. In addition, the sand in the cavity clogs the mesh provided in the vent plug, further deteriorating the flow of the curing gas.Therefore, the clogged plug must be removed with a drill each time. At the same time as removing the vent plug, it was necessary to insert a new vent plug, which was a very troublesome task.

(Purpose of the invention) This invention deals with the problems mentioned above.
By making it possible to exhaust the hardening gas in the cavity in the molding mold over a wide range, the hardening gas expands over a wide range in the cavity, so that the sand mold is sufficiently hardened,
To simplify the replacement work of a wire mesh for preventing sand leakage by making it possible to easily replace the wire mesh when it becomes clogged.

(Structure of the invention) In order to achieve the above object, the mold according to the invention is structured as follows.

That is, the above-mentioned mold body is arranged so as to be removable and has a molding cavity formed in the mating part, and a passage provided at a predetermined position for injecting sand and flowing hardening gas into the cavity. An exhaust passage that penetrates from the molding cavity to the outside is provided opposite to the passage, and the hardening gas flowing into the cavity is passed through the exhaust passage around the molding cavity side opening of the exhaust passage. An exhaust recess is formed that extends into the cavity from the inflow passage, and a wire mesh is provided to cover the opening of the exhaust passage and the exhaust recess. According to such a configuration, the curing gas is also exhausted from the exhaust recess formed around the cavity-side opening of the exhaust passage, so that the curing gas is expanded widely within the cavity from the inflow passage. In this way, the circulation of the curing gas is improved, and the sand mold is sufficiently hardened without leaving any unhardened parts. Further, even if the wire mesh covering the opening of the exhaust passage and the surrounding exhaust recess becomes clogged with sand, the wire mesh can be easily replaced.

(Example) The present invention will be described below based on an example shown in the drawings.

As shown in FIGS. 4 and 5, a concave molding cavity 2 is formed in the mating portion of the mold 1, and a plurality of exhaust passages 3...3, 4... communicate the cavity 2 with the outside. 4 are arranged. Here, this mold 1 forms a sand mold for casting a cylinder block of an engine, and the mold surface of the cavity 2 has a flat part 2a which becomes a baseboard part of the sand mold,
It has a cylindrical surface part 2b corresponding to the cylinder part of the product, and an uneven part 2c having a complicated uneven shape between both parts 2a and 2b.

However, among the exhaust passages 3...3, 4...4,
Groove-shaped exhaust recesses 5...5 are provided around the cavity side openings 3a...3a of the exhaust passages 3...3 provided in the flat portion 2a so as to communicate with the openings 3a...3a located nearby. Each of the recesses 5...5 communicates with each of the exhaust passages 3...3. Then, as shown in enlarged form in Figures 6 and 7,
A wire mesh 6 is stretched over the flat portion 2a so as to cover the cavity side openings 3a...3a of the exhaust passages 3...3 and the exhaust recesses 5...5. This wire mesh 6
are easily replaced and attached to the mold 1 by a plurality of screws 7...7.

In this embodiment, the cavity-side openings 4a...4a of the exhaust passages 4...4 provided in the cylindrical surface portion 2b and the uneven portion 2c of the cavity-shaped surface are provided with vent plugs having a net on the upper surface as in the conventional case. 8...
8 is entered. This is the cylindrical surface portion 2b.
Another reason is that it is difficult to stretch a wire mesh over the uneven portion 2c.

Next, the operation of the above embodiment will be explained.

First, as shown in FIG. 8, sand provided in the mold 11 is placed in a molding cavity 2 formed by a mold 1 and a mold 11 for an upper mold constructed in substantially the same manner as the mold 1. Sand a is introduced from the outside through the inflow passages 12...12. In that case, the cavity side openings 3a... of the exhaust passages 3...3 in the mold 1.
3a and the exhaust recesses 5...5 are covered with the wire mesh 6, and the cylindrical surface portion 2b of the cavity type surface
Vent plugs 8...8 with mesh are inserted into the openings 4a...4a of the exhaust passages 4...4 in the concavo-convex portions 2c, so these openings 3a...3
Sand a, 4a...4a and exhaust recesses 5...5 are prevented from leaking out. Further, as the sand flows in, the air inside the cavity 2 is discharged to the outside through the exhaust passages 3...3, 4...4.

Further, after the molding cavity 2 is filled with sand a, hardening gas is blown into the cavity 2 from the outside through the passage 12 of the mold 11.
After this hardening gas reacts with the sand and hardens the sand a, it is discharged to the outside from the exhaust passages 3...3, 4...4.
, the exhaust passages 3...3 face the hardening gas inflow passages 12...12, and the exhaust passages 3...3
Exhaust recesses 5...5 are provided around the openings 3a...3a to widen the exhaust surface, so that after the hardening gas flows in from the passage 12, it expands and hits the sand in the cavity 2. It will be widely supplied and distributed well. This forms a fully hardened sand mold.

By the way, the wire mesh 6 stretched along the mold surface of the cavity 2 as described above becomes clogged with the sand filling the cavity 2. As a result, the exhaust of the hardening gas is obstructed, and the wire mesh 6 must be replaced.
In that case, since the wire mesh 6 is removably attached to the mold 1 by screws 7...7, the screws 7...
The vent plugs can be removed by simply pulling out the vent plugs 7, which is much simpler than the conventional work in which the vent plugs are replaced one by one by being pulled out with a drill.

In the above embodiment, the exhaust recess provided around the cavity-side opening of the exhaust passage was configured as a groove-shaped part communicating with the opening, but as shown in FIG. 9, the cavity-side opening of the exhaust passage Part 3
Counterbore-shaped exhaust recesses 5'...5' are formed to surround a'...3a', and a wire mesh 6' is provided to cover these openings 3a'...3a' and exhaust recesses 5'...5'. It may also be a configuration.

In addition, the wire mesh covering the cavity side opening of the exhaust passage and the exhaust recess is not provided so as to be in close contact with the mold as in each of the above embodiments.
As shown in the figure, a protrusion 1b'' is provided on the cavity side surface 1a'' of the mold, and a wire mesh 6'' is attached to the protrusion 1b'' with screws 7''. A gap may be provided between the two.
In that case, this gap becomes the exhaust recess 5'', and the mold surface of the cavity is formed by the wire mesh 6''.

(Effects of the invention) As described above, according to the invention, the exhaust surface of the hardening gas blown into the cavity is widened, and the sand in the cavity is expanded from the inflow passage, and the hardening gas is supplied over a wide range. This results in a sufficiently hardened sand mold.
Further, if the wire mesh provided on the mold surface in the cavity becomes clogged, the wire mesh can be easily replaced, and the work to eliminate the clogging is greatly simplified.

[Brief explanation of the drawing]

1 to 3 show a conventional mold; FIG. 1 is a plan view, FIG. 2 is a cross-sectional view taken from FIG. 1, and FIG. 3 is a partially enlarged view of FIG. 2. Also,
Figures 4 to 10 show examples of the mold of the present invention, where Figure 4 is a plan view and Figure 5 is a
-V sectional view, FIGS. 6 and 7 are partially enlarged views of FIGS. FIG. 2 is a partially enlarged plan view and a partially enlarged sectional view showing an example. 1... Mold (mold body), 2... Molding cavity, 3, 4... Exhaust passage, 5, 5', 5''... Exhaust recess, 6, 6', 6''... Wire mesh.

Claims (1)

[Scope of utility model registration request] A mold body is arranged so as to be removable and has a molding cavity formed in the mating part, and a passage provided at a predetermined position for injecting sand and inflowing hardening gas into the cavity. An exhaust passage is provided facing the molding cavity and penetrating from the molding cavity to the outside, and the hardening gas flowing into the cavity is passed through the exhaust passage around the molding cavity side opening of the exhaust passage. A mold for molding, characterized in that an exhaust recess is formed to expand within the cavity from the inflow passage, and a wire mesh is disposed to cover the opening of the exhaust passage and the exhaust recess.