JPH01186244A - Manufacture of chill cam shaft - Google Patents

Abstract

PURPOSE:To take the chilling die for cam in one kind and to reduce the man/ hour in manufacture and fitting by cooling the chilling mold for cam of a cam shaft, forming the whole body shape consisting of a metal part and ceramic part in annular shape and molding a mold by fitting it to each cam position of a lost wax pattern. CONSTITUTION:The chill mold 1 for cam integrally forms a cooling metal part 2 and the ceramic part 3 composed of a shell sand. The cooling metal part 2 has the chilling inner peripheral mold face 4 coincident with the external shape of the cam nose part, which requires the chilling of the cam of the cam shaft to be cast. The ceramic part 3 has the nonchilling inner peripheral mold face 5 coincident with the external shape of the part excepting the cam nose part of a cam. The chilling mold 1 for cam mentioned above is fitted by aligning to the each cam position of the lost wax pattern 6 in the same shape as the cam shaft to be cast to mold the mold imbedding a lost wax pattern.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a camshaft for an engine, and more specifically, a method for manufacturing a chilled camshaft in which a cam nose portion of a cam is chilled using a chilled metal. Regarding.

[Prior Art] Generally, a single camshaft for an engine has eight cams (in the case of a camshaft for a four-cylinder engine) or twelve cams (in the case of a camshaft for a six-cylinder engine). These cams have a cam nose section, which is rotated at a predetermined angle around the axis of the camshaft, for example every 90 degrees (for a camshaft for a 4-cylinder engine) or every 60 degrees (for a camshaft for a 6-cylinder engine). ).

As a method for manufacturing a camshaft, there is a method of manufacturing a chilled camshaft by chilling a cam portion of a cast iron camshaft. In this case, a chiller is used to rapidly cool the cam portion where chilling is applied.

As disclosed in Japanese Utility Model Application Publication No. 50-77406 and Japanese Utility Model Application Publication No. 51-15107, the chiller used in the conventional manufacturing method of a chill camshaft is a half circumference of the cam of the camshaft. Some have a semicircular recess formed on the bottom surface that contacts only one part. Then, these cold metals are set in the upper and lower molds of the casting mold, respectively, and used. The combination of the upper and lower molds allows the two semicircular recesses to face each other, forming a cavity corresponding to the entire circumference of the cam. Also, the above-mentioned
In the chiller disclosed in Publication No. 1-15107, the concave part of the chiller contacts only the required part of the cam, and a gap is provided between the contact surface of the cam part other than the required part and the concave part of the chiller, and sand is filled. The system cools only the necessary parts of the camshaft. One way to set these chilled metals in the casting mold is to attach the chilled metal to the part of the camshaft that is to be chilled after the mold has been molded. After placing it on top, sand is poured into it and molded.

[Problems to be Solved by the Invention] As described above, the cam nose portion of the cam is arranged to be shifted by a predetermined angle around the axis of the camshaft. For this reason, in the conventional method using a chiller, the shape of the concave portion of the chiller must be changed depending on the angle of the cam nose of each cam, resulting in a large number of types of chillers. Therefore, the number of man-hours for manufacturing the chiller and the number of man-hours for sorting to set the chiller become large. Further, these chillers are set in the upper and lower molds of the casting mold, respectively. For this reason,
A fixing means is required to prevent the chiller attached to the upper mold from falling when the upper mold is inverted to match the upper mold to the lower mold. In general, the shape of the recess formed in the cold mold must not be undercut with respect to the direction in which the mold is removed. Therefore, depending on the orientation of the cam disposed on the camshaft, it may be necessary to provide a waste portion in addition to the outer shape of the cam.

Therefore, a cutting process or the like is required, which has a large cost disadvantage in the processing process.

In view of the above conventional drawbacks, the present invention has devised the shape of the chiller to simplify the setting of the chiller by consolidating one type of chiller, and also to reduce the waste area to prevent undercuts. It is an object of the present invention to provide a method for manufacturing a chill camshaft that does not require the provision of a chill camshaft.

[Means for Solving the Problems] The method for manufacturing a chilled camshaft of the present invention includes a chilled camshaft having a chilled inner peripheral mold surface that forms the outer shape of a cam nose portion of a cam of a cast camshaft that requires chilling. a non-chilled inner periphery that is formed integrally with the metal part and the chilled metal part, forms the outer shape of a portion of the cam other than the cam nose part, and forms a cavity space in which the cam is molded with the chilled inner mold surface; A cam chill mold having a ring-shaped overall shape and consisting of a ceramic part having a mold surface is attached to each cam position of a burnable model having the same shape as the chill camshaft, and the cam chill die is attached to the cam chill mold. The present invention is characterized in that a casting body in which the burnable model is embedded is formed based on the burnable model to form a mold, and molten metal is cast into the burnable model of the obtained mold.

The chill mold for a cam used in the chill camshaft manufacturing method of the present invention consists of a cold metal part and a ceramic part.

The chilled metal part forms the outer shape of the cam nose part of the cam shaft to be cast, and has a chilled inner peripheral mold surface that matches the outer shape of the cam nose part. The size and material of the cooling metal part can be appropriately selected depending on the required degree of chilling and the type of molten metal.

The ceramic part molds the outer shape of the cam of the camshaft to be cast, other than the cam nose part, and has a non-chilled inner peripheral mold surface that matches the outer shape of the part other than the cam nose part. The material for the ceramic part may be any material that does not cause the cam to chill and has sufficient strength to withstand the handling of the chill mold for the cam and the pressure of molten metal. Shell sand, raw sand, etc. preferable.

A ceramic part forming a non-chilled inner mold surface other than the chilled inner mold surface is integrally formed in the chilled metal part, and the chilled inner mold surface of the chilled metal part and the non-chilled inner mold surface of the ceramic part are integrally formed. The chilled inner mold surface forms an inner mold surface that matches the outer shape of the cam of the camshaft to be cast.

The chill-type cam only needs to have a ring-like overall shape, and its outer shape is not particularly limited. For example, it can be circular or polygonal.

The above-mentioned cam chill mold is attached to each cam position of a burnable model having the same shape as the chill camshaft to be cast. This burnable model is formed to have the same shape as the camshaft to be cast. The material may be any material as long as it is easily burned away by the heat of the melt field, similar to conventional burnable models, and a plastic foam such as polystyrene foam can be used. The cam chill mold is mounted by rotating the cam chill mold by a predetermined angle in accordance with the direction of each cam of the burnable model.

Moreover, it can also be performed automatically using a robot or the like.

The mold body for embedding the burnable model equipped with the chill mold for the cam can be made of green sand. It is also possible to form the lower half of the mold body with green sand or the like, attach a burnable model with the chill mold for the cam attached thereto, and form the remaining upper half by a squeeze mold filling method or the like. Further, both the upper half and the lower half of the mold body may be formed by a squeeze molding method or the like. Furthermore, even if the sprue part, the pusher part, etc. for injecting the molten metal are formed as burnable models,
Alternatively, it may be formed within the mold body.

As for the material of the mold body, raw sand or the like can be used as in the past.

Molten metal is mixed into the part of the burnable model through the sprue of the mold thus obtained. The burnable model disappears due to the heat of the molten metal, and instead, the shape of the burnable model is filled with molten metal, and a chilled camshaft having a cam nose section that is chilled in a chilled metal section is manufactured.

[Operations and Effects] According to the method for manufacturing a chill camshaft of the present invention, only one type of cam chill mold is used, which can accommodate cams of any angle, and the shape of the cam chill mold is one type. Can be done.

Therefore, compared to the conventional method in which a plurality of types of cam chill molds are required to manufacture one type of chill camshaft, the man-hours for manufacturing and mounting the cam chill mold can be reduced. Furthermore, depending on the direction of the cam nose part, it is no longer necessary to provide a useless part to prevent undercuts. Therefore, cost disadvantages in the processing process can be reduced. Furthermore, in the present invention, since the cam chill mold is attached to the burnable model, there is no need to take special consideration to fixing means for the cam chill mold. It is also easy to automatically store the chill type for the cam. Furthermore, it can be expected to prevent defects such as dust, etc., which are likely to occur due to damage to the mold when the chill mold for the cam is placed in the mold.

[Example] Hereinafter, this will be explained in detail using examples.

The chill mold 1 for a cam used in the embodiment of the present invention has a chill mold part 2 and a ceramic part 3 made of shell sand integrally formed, as its front view is shown in FIG. . The overall shape of this cam chill mold 1 is ring-shaped, and its outer shape is a perfect circle centered on the camshaft axis. In FIG. 1, a cross-sectional view taken along line A-A is shown in FIG.

The chilled part 2 has a chilled inner circumferential mold surface 4 having a substantially conical shape that matches the outer shape of a cam nose part of a camshaft to be cast, which requires chilling. Moreover, the ceramic part 3 is
It has a semicircular non-chilled inner circumferential surface 5 that matches the outer shape of the cam other than the cam nose. The chilled inner mold surface 4 and the non-chilled inner mold surface 5 together form an inner mold surface that matches the outer shape of the cam of the camshaft to be cast. The method of filling the ceramic part 3 into the chilled metal part 2 is not particularly limited, and conventional methods such as blowing and then firing can be used.

The cam chill mold 1 having the above-described configuration is attached to a burnable model 6 having the same shape as the chill camshaft to be cast, in accordance with the position of each cam. This burnable model 6 is made of polystyrene foam and is formed by molding or the like. As shown in FIG. 3, this cam chill mold 1 and burnable model 6
A burnable model 6 on which a chill mold 1 for a cam is mounted is disposed on a lower mold 7 in which a recess 7a corresponding to a half portion of the integrated body is cut along a plane passing through the shaft axis.

A plan view at this time is shown in FIG. 4, and a sectional view taken along line A--A in FIG. 3 is shown in FIG. 5.

Next, as shown in FIG. 6, a casting flask 8 is placed around the lower die 7, green sand 9 is put into the flask, and then pressure is applied by a squeeze plate 10 to compress the green sand 9. In this way, a lower mold matrix 11 is obtained in which the cam chill mold 1 and the burnable mold 6 are fixed in green sand 9 in one piece. Furthermore, surface plate 12
A wooden model 13 corresponding to a half part of an integral body of a cam chill mold 1 and a burnable model 6 cut along a plane passing through the shaft axis is fixed on top. Then, as shown in FIG. 7, in the same way as the lower mold mother mold 11, a casting flask 8 is placed over the mold, green sand 9 is poured into the frame, the green sand 9 is compressed by the squeeze plate 10, and the upper mold A matrix 14 is obtained.

The lower mold mother mold 11 and the upper mold mother mold 14 thus obtained are combined to obtain a mold. A cross-sectional view of the cam part of this mold taken along a plane perpendicular to the shaft axis is shown in FIG. 8, and a cross-sectional view taken along a plane passing through the shaft axis is shown in FIG. 9. Then, the molten metal is supplied to the burnable model 6 from a deep mouth (not shown). The burnable model 6 disappears due to the heat of the molten metal, and the shape of the burnable model is filled with molten metal instead. In this way, a chilled camshaft having a cam nose section chilled by the cold metal section is obtained.

As described above, according to the chill camshaft manufacturing method of this embodiment, the same cam chill mold can be used for any cam in the burnable model 7, and the type of cam chill mold can be changed to one type. It can be of any kind.

Therefore, it was possible to reduce the number of man-hours for manufacturing and mounting the chill mold for the cam. In addition, since it is not limited by the direction of the cam part, the degree of freedom in designing the camshaft is increased, and it is easy to respond to changes in the design.Furthermore, there is no need to provide a wasteful part and a cutting process is not required. do not.

[Brief explanation of the drawing]

Fig. 1 is a front view of the cam chill mold used in the example, Fig. 2 is a cross-sectional view taken along the line A-A in Fig. 1, and Fig. 3 is a burn-out property with the above-mentioned cam chill mold attached. Fig. 4 is a plan view of Fig. 3 viewed from above, Fig. 5 is a sectional view taken along line A-A in Fig. 3, and Fig. 6 is a bottom view showing the model housed in the lower mold. Figure 7 is an explanatory diagram of molding the upper mold matrix, Figure 8 is a cross-sectional view of the mold taken along a plane perpendicular to the shaft axis at the cam portion, and Figure 9 is an explanatory diagram of molding the upper mold matrix. Each figure shows a cross-sectional view of the mold taken along a plane passing through the shaft axis. 1... Chill mold for cam, 2... Chilled metal part, 3... Ceramic part, 4... Chilled inner circumferential mold surface, 5 Non-chilling part. Chilled inner peripheral mold surface, 6...
Burnable model, 7...lower mold, 8...
...Casting flask, 9...Green sand, 10...
... Squeeze plate, 11 ... Lower mold matrix, 13 ... Model, 14 ... Upper mold mother mold Patent applicant Toyota Motor Corporation agent
Patent Attorney Hiroshi OkawaFigure 1Figure 2ΔFigure 4Figure 6Figure 8Figure 7Figure 9

Claims (1)

[Claims] (1) Among the cams of the camshaft to be cast, a chilled metal part having a chilled inner peripheral mold surface that forms the outer shape of the cam nose part that requires chilling, and a chilled metal part that is integrally formed with the chilled metal part, For cams whose overall shape is ring-shaped, consisting of a ceramic part having a non-chilled inner peripheral mold surface that forms a cavity space in which the cam is molded with the chilled inner peripheral mold surface by molding the outer shape of the parts other than the cam nose part. A chill mold is sandwiched at each cam position of a burnable model having the same shape as a chill camshaft, and a casting body is formed in which the burnable model is embedded based on the burnable model to which the chill mold for the cam is attached. A method for producing a chill camshaft, comprising: forming a mold, and casting molten metal into the burnable model of the obtained mold.