JPS6076251A - Molding method of shell mold for casting - Google Patents

Abstract

PURPOSE:To improve rigidity and shape accuracy of a shell mold for casting in the stage of adhering a pair of half-split shell mold materials and molding the shell mold by incorporating reinforcing rods into the half-split molds and utilizing the same as receiving seats for bonding. CONSTITUTION:Two reinforcing rods 22 are disposed with a pattern part 21 for a cam shaft formed on a pattern plate 20 in-between in the stage of casting a cam shaft by using a shell mold for casting. Receiving members 24 which are receiving seats for bonding are fixed to the plural positions on the top surface of the rods 22. After such pattern plate 20 is heated in an electrical furnace, the plate is set in a dump box 27 and chillers 30 are attached to the prescribed parts of the pattern 21. Resin sand 31 is put into the box 27 and after the sand is molded and melt-stuck, the resin sand layer is parted, calcined and cured, by which a half-split shell mold 32 is manufactured. Two pieces of such molds are combined and bonding pins 34 are press-welded to the members 24. Both half- split molds are adhered and the shell mold having the excellent rigidity provided by the reinforcing rods and having excellent shape accuracy is molded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for making a shell mold used in the shell mold method, which is a type of precision casting method, and in particular improves the rigidity of the shell mold. The present invention also relates to a shell mold making method that improves the precision of a honding seat, which is a reference surface when combining and joining pairs of half-shaped shell casting materials.

(Prior art) The shell molding method, which is a type of precision casting method, can cast castings with high dimensional accuracy and does not require skill in the casting work, so it is very advantageous in mechanizing the casting process, and it is very advantageous when it comes to mechanizing the casting process. It has long been well known that it is suitable for mass production.

Therefore, in recent years, important parts with complex shapes such as engine camshafts have been cast using shell molding to reduce machining as much as possible and improve productivity.

Incidentally, the shell mold used in this shell mold method is generally molded by a method called the dump method, and the technology related to the method of manufacturing this shell mold is disclosed in, for example, Japanese Patent Laid-Open No. 58
It is disclosed in the publication No.-41649.

As shown in FIGS. 1 to 3, in this prior art, the lower shell mold material 2 formed on the pattern plate 1 is first formed on the pattern plate 1 by a dumping method using a tamp box or the like before it hardens. A forming pin 5 placed at the same position as the reference pin 4 of the lower mold pounding plate 3 is pressed by a pressure forming plate 6 to form a flat portion 8 on the flange portion 7 of the shell mold 2. Next, the shell mold material 2 released from the pattern plate 1 after firing and hardening is firmly supported by the flat portion 8 on the reference pin 3 fixed to the lower mold pounding plate 3 with the mating surface 9 facing upward. Meanwhile, in this state 7g, the shell mold is pressed by the upper mold bonding plate 12 through the pounding pin 11 having the spring 10 to bond the shell mold material 13 of the mold to the shell mold material 2. This is the molding method.

However, if such a prior art is used to make a shell mold for the aforementioned long part of the camshaft, the rigidity of the shell I/f4 type will be insufficient because it is a shell mold or fl. There was a problem in which the shell mold was deformed during casting due to the weight of the molten metal. When the shell mold deforms, the casting also deforms, creating the problem of increased machining required to correct this deformation.

Furthermore, since the flat portion 8 is formed by pressing the forming pin 5, there is a limit to its dimensional accuracy, and both shells #j'
It has been difficult to further improve the precision of the MAJ method for the bonding seat, that is, the flat portion 8, which serves as a reference surface when bonding the I-shaped materials 2 and 13.

(Object of the Invention) The present invention has been made in consideration of the above circumstances, and its purpose is to improve the rigidity of the shell mold to prevent deformation of the shell mold due to the weight of molten metal during casting. To provide a shell mold manufacturing method which can improve the accuracy of a reference surface, that is, a bonding seat when combining and bonding a pair of half-shaped shell mold materials, and thereby improve the accuracy of the shell mold.

(Structure of the Invention) In order to achieve this object, the present invention is structured as follows. That is, a reinforcing member is provided along the pattern portion of the pattern plate for at least one of the pair of shell Hm materials in the shape of a student discount, and a plurality of positions of the reinforcing member are pressed by loft presser pins provided on the dump box to form the pattern. The plate is supported, and in this state, resin sand is welded around the pattern plate to expose the suppressed portion of the reinforcing rod as a ponting seat, and a shell #4 mold containing the reinforcing rod is molded. The method is to press the pounding seat with a pounding pin, and then combine and bond one shell mold material and the other shell mold material together. With this configuration, at least one of the N-type shell materials includes a reinforcing rod, which improves the rigidity of the shell mold, and also exposes the opening of the reinforcing rond and the part pressed by the nd holding pin, so that it can be used as a pounding seat. This improves the accuracy of the honding catch.

(Embodiment) An embodiment of the present invention will be described with reference to FIGS. 4 to 7. In FIG. 4, a shows a step of arranging the reinforcing rod IS, and in this step a, as shown in FIG.
- Two wooden reinforcing openings 22 are arranged sandwiching the pattern part 21 of the camshaft formed in the camshaft. This reinforcing port/end 22 is made of a steel pipe with sufficient bending rigidity.
Bracket 23 protruding above pattern play 1/20
It is placed on. Furthermore, receiving members 24 serving as pounding seats are fixed at a plurality of predetermined positions on the upper surface of the reinforcing port/end 22, that is, directly above the grating 23 and at the center between the brackets 23. Further, the pattern plate 20 has a sprue 25. A runner 26 is provided.

The entire pattern plate 20 is processed in step b in FIG.
(Heating step) The pattern plate 20 is housed in an electric furnace and heated to a predetermined temperature, and then proceeds to the next step C. This step C is a step in which the heated pattern plate 20 is set in a dump box.

As shown in FIG. 6, a presser pin 28 is resiliently installed in the tamper box 27. This mouth/end holding pin 28 is provided so as to face the receiving member 24 of the reinforcing rod I/22 so as to press the receiving member 24 with a spring 29. The pattern plate 20 in the dump box 27 is supported by the opening and holding pins 28 and set in the dump box 2f. At this time, the receiving member 24
The lower end surface of the opening/do presser pin 28 is in close contact with the upper surface, and the upper surface of the receiving member 24 is covered by the lower end surface of the opening/do presser pin 28. Further, a chiller called a chiller 30 is provided on the outer peripheral surface of the cam profile portion of the pattern portion 21, and the chiller 30 rapidly cools the surface of the cam profile portion during casting to form a chill structure and harden it.

A resin cant 31 is stored in advance in such a dump box 2, and in the next step d (molding step of the shell mold material), the dump box 27 is inverted.
The resin component melts and sticks to the surface of the pattern plate 20 in a layered manner. A reinforcing rod 22. A chiller 30 is included, and the surface of the receiving member 24 of the reinforcing iron 22 is exposed from the resin sand layer. The resin sand layer that has been hardened to some extent in this state is released from the mold, then fired and hardened to be molded as a shell mold material.

Since such a shell mold material has a half-split shape as shown in FIG. 7, a pair of shell mold materials 3233 are combined and bonded in step d, which is a bonding step. At this time, the pounding pin 34 that presses the picture materials 32 and 33 comes into contact with the receiving member 24 that is exposed and protruded from the surface of the picture materials 32 and 33, and presses the picture materials 32 and 33, and this state The picture materials 32 and 33 are then glued together to complete the shell mold.

The mold molded by the method of the above embodiment has the following advantages.

First, since the reinforcing port 22 is included along the pattern part 21, the rigidity of the mold material 32, 33 is improved, and the weight of the injected molten metal is reduced. The shell mold can be prevented from being deformed.

Next, in the honding step d of the picture materials 32, 33, the receiving member 24 exposed from the surface of the picture materials 32, 33 can be used as a bonding ink receiving seat, so the picture materials 32, 33 are combined. The positional force of the reference surface, that is, the pounding seat when making one bottom contact (the positional force becomes accurate, and the accuracy of the shell mold can be improved).

Note that the present invention is not limited to the above embodiment. For example, the pair of shell mold materials 32 and 33 are not limited to both molded by steps a to d of the present invention, and it is sufficient that at least one of them is molded by steps a to d of the present invention.

(Effects of the Invention) As explained above, according to the present invention, the rigidity of the shell mold is improved to prevent the shell mold from being deformed during casting, and when bonding a pair of half-shaped shell T4J molds, By improving the accuracy of the pounding catch that serves as the reference surface,
Because we can provide a shell mold manufacturing method that can improve the accuracy of shell molds.

The effect is great. .

[Brief explanation of the drawing]

FIGS. 1 to 3 are explanatory diagrams showing conventional examples, respectively, and FIGS. 4 to 7 are diagrams showing an embodiment of the present invention.
The figure is a process diagram, FIG. 5 is a perspective view of the pattern plate 20,
FIG. 6 is a longitudinal sectional view of the tump box 27, and FIG. 7 is a longitudinal sectional view of the shell mold. a... Reinforcement rod placement process b... Heating process C... Pattern plate setting process d... Shell mold material forming process e... Honing process 2o... Pattern plate 21... Pattern portion 22...Reinforcement rod 24...Receiving member (Bonde ink receiver) 27...Tassopponx 31...Resin Santo 23.33...Shell mold material patent applicant Toyo Kogyo Co., Ltd. Agent Patent attorney Suzu t [filial]

Claims (1)

[Claims] (1) A method of molding a shell mold by bonding a pair of semicircular shell mold materials, in which at least one of the shell mold materials is manufactured through the following steps a to d, and these The method is characterized in that the following bonding seat formed on the shell mold material formed through the process is pressed with a pounding pin, and the one shell mold material and the other shell mold material are combined and bonded. Shell mold manufacturing method. , a plurality of reinforcing ronds are arranged along the pattern portion of the pattern plate. b. Heating the pattern plate together with this reinforcing iron. C0 Press the reinforcing rod with a rod holding pin installed in the dump box so as to face a plurality of predetermined positions of the reinforcing rod, and dump the pattern plate by supporting the pattern plate at the suppressed portion of the reinforcing rod. Set it in the box. d. In this state, resin sand is applied to the pattern plate 1 to expose the suppressed portion of the reinforcing rod as a pounding seat, and a halved shell mold material containing the reinforcing rod is formed.