JPH0729153B2 - Method for manufacturing rough cast product for press die - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a rough cast product used for a press die.

[Prior Art] Conventionally, a rough cast product for a press die is generally manufactured by a full molding method. For example, in the full molding method disclosed in Japanese Patent Laid-Open No. 61-266147, as shown in FIGS. 8 and 9, first, a model 100 corresponding to a press die 600 (see FIG. 13) is made of expanded polystyrene. To do. Then, as shown in FIG. 10, after setting the model 100 and the mold 201 on the surface plate 200, the molding sand 300 mixed with the self-hardening resin is put between the model 100 and the mold 201 and tamped. , Leave until the molding sand 300 is hardened. Next, as shown in FIG. 11, the mold 201 is reversed, another mold 202 is placed, and the molding sand 300 is put in again and tamped to harden the molding sand 300. After that, the model 100 is extinguished by pouring from the sprue 400, and the rough cast product 5 shown in FIG.
Get 00.

The obtained rough cast product 500 has a bottom surface 501 and a key groove 5 with reference to a machining reference groove formed from a model reference groove 100a provided in an appropriate number of positions in the model 100 (see FIGS. 8 and 9).
02 and are machined. Then, as shown in FIG.
The bottom surface 501 and the key groove 502 are used as a reference for NC processing or model copying processing, and the molding surface 601 of the press die 600 is ground.

[Problems to be Solved by the Invention] However, in the above conventional manufacturing method, the dimensional accuracy of the obtained rough cast product is poor, and there are various problems until the press die is completed.

That is, the model 100 shown in FIG. 8 is made of styrofoam, and is wholly manufactured to substantially correspond to the press die 600 (see FIG. 13). At this time, the model 100 is also manufactured by adhesion or stacking, and during processing, deformation or peeling is likely to occur due to the material characteristics. Moreover, the model surface 101 corresponding to the molding surface 601 is, at best, NC-processed the Styrofoam raw material under the conditions of a ball end mill of φ30 mm and a pick feed of 20 mm, or by taking a cross-section gauge every 100 mm and then performing a 100 mm interval. It is often formed by finishing or by machining, and the residual of the cutter mark, the deformation due to cutting resistance, and the cumulative error in the processing technique such as rough hand finishing greatly reduce the dimensional accuracy of the model 100. in addition,
Since the model 100 itself is accompanied by irregular compressive deformation due to sand compaction pressure during the mold filling shown in FIGS. 10 and 11,
The decrease in accuracy is further promoted. Then, the reference surface processing of the bottom surface 501 and the processing of the key groove 502 of the obtained rough cast product 500 are processed with the processing reference groove 100a as a reference, but the processing reference groove 100a is far from the forming surface 601, so that the forming is performed. Model dimensional accuracy error, mold deformation error, shrinkage error during casting cooling, etc. are piled up on the surface 601, and the error on the molding surface 601 is further amplified, and the allowance T considering the safety level varies widely from 10 to 30 mm. It will be. It should be noted that the larger the machining allowance T is, the larger the influence of the working strain due to the residual stress is, and therefore, it is necessary to add a new working process such as reworking the warp of the bottom surface 501. Of course, if all press dies that are not mass-produced products are to be cast with sand molds, the casting method itself including the expensive model cost is already disqualified from the economical aspect.

The present invention provides a technical problem to be solved for producing a highly accurate rough cast product for a press die without impairing economy.

[Means for Solving the Problem] In order to solve the above-mentioned problems, the method for manufacturing a rough cast product for a press die of the present invention produces a casting model having a model surface corresponding to the molding surface of the press die. , A step of molding a sand mold in which the model surface is copied by molding the casting model, and manufacturing an extinction model corresponding to the structural part of the press mold,
A new process comprising the steps of aligning this with the sand mold, molding it into a finished mold, and pouring it into a cavity formed containing the vanishing model to obtain a rough cast product. We have adopted various means.

[Operation] In the present invention, the completed mold is formed by combining the sand mold for casting the complicated molding surface of the press die and the relatively low precision disappearance model for casting the simple structure portion. In addition to improving the precision of the molding surface itself, the matching surface of the sand mold combined with the vanishing model provides an accurate machining reference surface in the vicinity of the molding surface of the rough cast product, so processing of the molding surface The stock removal can be set extremely small. Therefore, the processing-related man-hours of the press die are significantly reduced without significantly increasing the burden related to casting.

Embodiments Embodiments embodying the present invention will be described below with reference to the drawings. This example manufactures a rough cast product for a press die for pressing an automobile door.

First, as shown in FIG. 2, a casting model 1 was manufactured. This casting model 1 includes a prototype simplified model 10 made of zinc-aluminum alloy shown in FIG. 1, and a positioning member 11 provided at an end of the prototype simplified model 10.
And a sheet wax layer 12 having a thickness of about 3 mm, which is provided on the surface of the prototype simplified model 10 by the amount corresponding to the machining allowance.

The prototype simplified model 10 is a simple casting model used when making prototypes of automobile doors.
A contraction allowance of 10/1000 is expected. By using this simple prototype model 10, it is possible to effectively use the conventional waste products. In addition, this prototype simple model
Relief 1a, 1b that does not require processing for recesses of 10 or less than 8R
Is formed.

The positioning member 11 has a horizontal upper surface as a model reference surface 20, and the model reference surface 20 has an appropriate number of positioning locating pins.
A hole 1c that engages with 21 is formed.

Thus, in this casting model 1, the surface of the sheet wax layer 12 is the molding surface of the press die 9 (see FIG. 7).
It is a model surface 12a corresponding to 91. If the prototype simplified model 10 is not used, the casting model 1 may be molded with gypsum, porcelain clay, or the like, or a prototype pressed product or a copying model may be used.

Next, as shown in FIG. 3, the outer periphery of the casting model 1 is surrounded by a mold 41, and after the locating pin 21 is engaged with the hole 1c, a molding sand mixed with a self-hardening resin is put, tamped and left. Cured. In this way, the sand mold 3 in which the model surface 12a is copied is formed. In this sand mold 3, a horizontal matching surface 22 is formed by the model reference surface 20, and a locate pin 21 is embedded in a predetermined position of the matching surface 22.

In parallel with the steps of manufacturing and molding the casting model 1, as shown in FIG. 4, the structure portion 92 of the press mold 9 is formed.
An extinguishable model 5 corresponding to (Fig. 7) was made of styrofoam. In the disappearing model 5, a contact surface with the matching surface 22 of the sand mold 3 is a horizontal disappearing reference surface 23, and a hole 5a for engaging the locate pin 21 is formed at a predetermined position of the disappearing reference surface 23. Since the disappearing model 5 is manufactured with a relatively low accuracy at the same time as the casting model 1 is manufactured, it contributes to the reduction of the number of manufacturing days of the rough cast product 8 (Fig. 6).

Then, as shown in FIG. 5, the sand mold 3 was set on the surface plate 40, and the disappearing model 5 was placed on the sand mold 3 while engaging the locate pin 21 with the hole 5a. At this time, the molding surface of the sand mold 3
Since the sand mold model surface 31 corresponding to 91 can be visually recognized, it is possible to prevent defects of the rough cast product 8 in advance. After this, the formwork
No. 42 was installed, and molding sand was put thereinto and tamped and hardened. In this way, the finished mold 7 was molded.

Next, the space 6 formed between the sand mold molding surface 31 of the sand mold 3 and the disappearance model 5 and the cavity 60 formed by the disappearance model 5 itself are poured from the sprue 71 into the cavity 60. The disappearing model 5 was disappeared and filled with molten metal. After cooling, the rough cast product 8 shown in FIG. 6 was obtained. In the rough cast product 8 thus obtained, an accurate rough forming surface 80 is formed by the sand mold forming surface 31, and at the same time, an accurate processing reference surface near the rough forming surface 80 is formed by the matching surface 22.
24 are formed.

Then, the rough cast product 8 has a bottom surface 81 and a key groove 82 which are machined with the machining reference surface 24 and the locate pin 21 as a reference, and the rough forming die surface 80 is machined by a machining allowance T with reference to the machining surface. Be seen. At this time, the machining allowance T of the rough forming surface 80 is almost
Accurate and evenly added with 3mm. Therefore, the fully formed operation can be fully utilized to process the rough forming surface 80 in an extremely short time. It should be noted that maintenance costs for cutting tools and machines, reduction of dust and cutting costs, etc. are also effects that are hard to overlook.

Therefore, according to the manufacturing method of the present embodiment, it is possible to significantly reduce the processing-related man-hours of the press die without significantly increasing the burden of casting.

[Effects of the Invention] As described in detail above, in the manufacturing method of the present invention, a highly accurate sand mold for casting a complicated molding surface of a press die and a relatively low accuracy for casting a simple structure part disappear. Since it is combined with the sex model, it is possible to obtain a rough cast product with excellent dimensional accuracy without impairing economic efficiency. Therefore, according to the manufacturing method of the present invention, a press die can be obtained with good working efficiency.

In the manufacturing method of the present invention, since it is possible to manufacture a rough cast product with a small machining allowance using a casting model, unnecessary parts of the molding surface of the press mold currently being machined, the profile and the steel material. It is also possible to leave the insert part as the casting surface and omit the processing, thereby reducing the number of steps. In addition, it is possible to reduce the man-hours for the steel insert part and the structure part for the rough cast product with a small stock removal.

[Brief description of drawings]

1 to 7 show one embodiment of the present invention, FIG. 1 is a sectional view of a prototype simplified model, FIG. 2 is a sectional view of a casting model, and FIG. 3 is a sectional view of a casting model and a sand mold, FIG. 4 is a cross-sectional view of the vanishing model, FIG. 5 is a cross-sectional view of a completed mold, FIG. 6 is a cross-sectional view of a rough cast product, and FIG. 7 is a cross-sectional view of a press die. 8 to 13 show the conventional manufacturing method, FIG. 8 is a sectional view of the model, FIG. 9 is a partial side view of the model shown in FIG. 8, and FIGS. FIG. 12 is a sectional view showing a state, FIG. 12 is a sectional view of a rough cast product, and FIG. 13 is a sectional view of a press die. 1 …… Casting model 12a …… Model surface, 3 …… Sand mold 5 …… Disappearance model, 60 …… Cavity 7 …… Complete mold, 8 …… Rough cast product 9 …… Press mold, 91 …… Molding surface 92 …… Structure part

Claims (1)

[Claims] 1. A step of producing a casting model having a model surface corresponding to a molding surface of a press die, and molding the casting model to mold a sand mold in which the model surface is copied, and the press. We made an extinction model corresponding to the structure of the mold,
This is composed of the steps of aligning this with the sand mold and then molding it into a finished mold, and pouring into the cavity formed containing the vanishing model to obtain a rough cast product. A method for producing a rough cast product for a press die, which is characterized.