JP4482264B2 - Mold for resin molding - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a resin molding die, and more particularly, to a resin molding die that does not require processing work and that provides high surface accuracy.
[0002]
[Prior art]
Conventionally, in order to manufacture a mold for resin molding, a mold steel such as forged carbon steel is prepared, and the mold steel is cut into a mold shape, or a spherical shape with a fine graphite particle size is formed. It was cast into a generally mold shape with graphite and CV cast iron, and the molding surface of the mold was further finished by polishing or the like so as to have a predetermined accuracy.
[0003]
[Problems to be solved by the invention]
However, when using forged carbon steel, etc., it is gradually cut out from the mold steel block, and the mold is formed, which requires a lot of work and labor, production days, production costs, etc. There was something that would get bigger. In addition, since the material was gradually cut out from the block, there was a lot of wasted material generated during the cutting.
[0004]
On the other hand, in the case of manufacturing by casting, since the processed part is almost only the molding surface, the processing time is less than in the case of molding from forging, but a minute shrinkage (micro shrinkage) occurs on the molding surface due to casting. Sometimes. If micro-shrinkage occurs on the molding surface, the micro-shrinkage is transferred to the surface of the molded resin molded product, which is not preferable because a protruding protrusion is formed.
[0005]
An object of the present invention is to provide a mold for resin molding that is easy to process and has high finishing accuracy.
[0006]
[Means for Solving the Problems]
In the present invention, in order to solve the above problems, a resin molding die is configured as follows.
[0007]
In a resin molding die formed of flake graphite cast iron having a D-type graphite structure, the flake graphite cast iron having the D-type graphite structure is formed on the molding surface by applying Ti to the mold surface, and is flat. A resin molding die having an average length of 0.05 mm or less when observed and an average distance between the graphites of 0.02 mm or less was formed.
[0009]
A resin molding die having C of 2.6 to 3.8 wt%, Si of 1.2 to 2.6 wt%, and a carbon equivalent (CE) of 4.3 or less was formed.
[0014]
The proportion of D-type graphite on the molding surface is desirably 50% or more. When the chiller is used, since the eutectic cell becomes fine, it may be 20% or more.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
A method for producing a resin mold according to the present invention will be described.
[0016]
As shown in FIG. 1, the resin molding die 2 is composed of a pair of molds, and the resin molding surface 4 of each inner surface is a D-type graphite structure 6. 6 and 7 show examples of the D-type graphite structure. As shown in the figure, it can be seen that the graphite is D-type graphite.
[0017]
FIG. 8 shows a structure other than the D-type graphite structure.
[0018]
In particular, when the cross section of the D-type graphite structure 6 is observed, the average length of graphite is preferably 0.05 mm or less, and the average distance between adjacent graphites is preferably 0.02 mm or less. C is 2.6 to 3.8 wt%, Si is 1.2 to 2.6 wt%, and the carbon equivalent (CE) is 4.3 or less.
[0019]
In general, graphite is continuous in a metal, and it is necessary to have the above as observed in a cross section. When C is 2.6 wt% or less, chilling and shrinkage are likely to occur, and when it is 3.8 wt% or more, the graphite becomes coarse and the surface roughness of the mold deteriorates. Moreover, when it becomes a hypereutectic component, coarse quiche graphite (C-type graphite) will appear, and surface roughness will worsen.
[0020]
When Si is 1.2 wt% or less, it becomes chill, and when it is 2.6 wt% or more, the graphite becomes coarse and the surface roughness of the mold deteriorates. The carbon equivalent (CE) is in the range of 3.0 to 4.3. If the amount is small, chilling and shrinkage nests are likely to occur. If the amount is large, graphite becomes coarse and the surface roughness of the mold deteriorates. The graphite equivalent is an amount of graphite converted including a component having the same function as graphite. In the case of Si, it is calculated by C + 1 / 3Si.
[0021]
In order to make the molding surface 4 of the mold 2 have a D-type graphite structure 6, as shown in FIG. 2, when the resin molding mold 2 is molded by casting, a cooling mold 10 is appropriately disposed inside the mold 8. . Thereby, the cooling rate of the molding surface 4 is increased, and the molding surface 4 becomes the D-type graphite structure 6. When a mold master having the D-type graphite structure 6 formed on the molding surface 4 by casting is manufactured, finishing operations such as polishing of the molding surface 6 are performed to complete the resin molding die 2.
[0022]
When the cooling rate is increased with the cooling metal 10 or the like, the amount of pearlite is relatively increased, and the addition of Cu and Ni can be reduced. Since the D-type graphite structure is likely to become ferrite, Cu or Ni may be added to make it pearlite to prevent the formation of sink marks.
[0023]
Next, another example of the mold manufacturing method will be described. In this example, a predetermined amount of Ti is added to cast iron, and the mold prototype of the resin molding mold 2 is cast to form a mold prototype composed of a D-type graphite structure. In this manner, when a mold master having a D-type graphite structure is manufactured, the molding surface 4 is polished and the resin molding mold 2 is completed.
[0024]
When Ti is added to form the D-type graphite structure 6, it is preferable to add Ti three times or more to S in cast iron water. Also, Cu or Ni is added to make the base pearlite. Further, the pearlite ratio can be increased by increasing the Mn content or by adding elements such as Cr and Mo. In this case, however, an increase in sinkability is observed. The addition of elements such as Mn, Cr, Mo, P and V is not preferable because the micro shrinkage increases.
[0025]
Further, Ti is added to the cast iron hot water, and the entire mold master is cast iron having a D-type graphite structure. However, the present invention is not limited to this, and the inner surface of the mold 8 for casting a resin mold as shown in FIG. That is, Ti may be applied in advance to a portion to be the molding surface 4. As described above, when Ti is applied to the inner surface of the mold 8 for casting the resin molding die 2 and cast, the Ti content in the vicinity of the molding surface 4 of the resin molding die 2 is increased. As shown, the molding surface 4 can be formed in a D-type graphite structure 6. Thereby, the smoothness of the surface of the molding surface 4 was high, and it was possible to mold a high-quality resin molding die 2 that does not cause peeling.
[0026]
Moreover, as shown in FIG. 4, the forged product 5 formed in the shape of the molding surface 4 in the part of the molding surface 4 may be used, and the other location of the resin molding die 3 may be formed by casting. According to this, since the molding surface 4 can be a forged product 5, the occurrence of micro shrinkage can be prevented, and the forging block need not be cut, and the resin molding die 3 can be easily processed. Further, as shown in FIG. 5, the pipe 12 may be arranged in advance on the back surface of the forged product 5.
[0027]
【The invention's effect】
Since the resin molding surface is formed with the resin molding surface of the resin molding die as a D-type graphite structure, there is no surface peeling during processing or polishing, and there is no micro-shrinkage. A mold can be obtained. In addition, the molding surface can have high specularity. Moreover, since the graphite shape is a fine D shape, the workability of the molding surface is also good.
[0028]
Furthermore, if the molding surface is molded in advance with a forged product and the other portions other than the molding surface are molded by casting, a resin shaping mold having a highly accurate molding surface can be easily molded.
[Brief description of the drawings]
FIG. 1 is a view showing a resin molding die of the present invention.
FIG. 2 is a view showing an example of molding a resin molding die of the present invention.
FIG. 3 is a view showing another example of molding the resin mold according to the present invention.
FIG. 4 is a view showing another example of a resin mold according to the present invention.
FIG. 5 is a view showing another example of a resin molding die according to the present invention.
FIG. 6 is a diagram showing an organization.
FIG. 7 is a diagram showing an organization.
FIG. 8 is a diagram showing each organization.
[Explanation of symbols]
2, 3 Mold for resin molding 4 Molding surface 5 Forged product 6 D-type graphite structure 8 Mold 10 Cooling metal 12 Pipe

Claims (2)

  In a resin molding die formed of flake graphite cast iron having a D-type graphite structure, the D-type graphite structure is formed on the surface by applying Ti to the mold surface, and the average length when observed in a plane Is a graphite having a thickness of 0.05 mm or less, and an average distance between the graphites is 0.02 mm or less. 2. The resin molding according to claim 1, wherein C is 2.6 to 3.8 wt%, Si is 1.2 to 2.6 wt%, and a carbon equivalent (CE) is 4.3 or less . Mold.

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