JP3744695B2 - Mold manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mold manufacturing method and a mold in which a material of a main part that receives a large stress during processing of a workpiece and a material of a mold main body that supports the main part are different.
[0002]
[Prior art]
Since the die body of the press die is usually manufactured by casting, the cast body is preferably made of gray cast iron which has good castability and is easy to cut after casting. On the other hand, as the material for the cutting blade part and bending blade part (hereinafter referred to as “main part”) of the press mold, tool steel having higher hardness than the mold body is preferably used in consideration of wear resistance and the like. For this reason, the press mold is generally manufactured by assembling a main part separately manufactured to the mold body (see FIG. 7).
In the assembling operation of the main part 4, first, the receiving part 2 u of the mold body 2 to which the main part 4 is assembled is machined in order to obtain assembling accuracy. Next, a rubbing operation for adjusting the position of the main part 4 with respect to the mold body 2 is performed. In this way, when the position adjustment of the main part 4 is completed, the main part 4 is fixed to the mold body 2 by the bolts 6, knocks 7, and the like.
[0003]
[Problems to be solved by the invention]
In the manufacturing method of the press mold 1 described above, when the main part 4 is assembled to the mold main body 2, the machining of the receiving part 2 u of the mold main body 2, the position adjustment of the main part 4, and the necessity for the mold main body 2 are required. Since fixing of the part 4 is required, skill is required for work, and a long assembling time is required. In particular, in the press mold 1 in which a large number of main parts 4 are connected to form a bent part, it is necessary to adjust the positions of the main parts 4, so that the assembly time is further increased. For this reason, there exists a problem that the manufacturing cost of the press die 1 becomes high.
[0004]
Therefore, the invention according to claim 1 of the present invention is such that a mold having different materials for the main part and the mold body can be integrally formed by casting, and the main part and the mold body are separately manufactured. An object of the present invention is to reduce the manufacturing cost of the mold by eliminating the assembling work required for the integration.
In addition to the object of the invention described in claim 1, the invention described in claim 2, claim 3, and claim 5 narrows the mixing range of the material of the mold body and the material of the main part as much as possible. For the purpose.
In addition to the object of the invention described in claim 1, the inventions described in claim 4 and claims 6 to 8 aim to strengthen the connection between the mold body and the main part. .
[0005]
[Means for Solving the Problems]
The above-described problems are solved by a mold manufacturing method having the following characteristics.
That is, the production method of a mold according to claim 1 is a method of manufacturing a mold that the material of the main part and the material of the mold body to support the main portion thereof is different from receiving a large stress during processing of the workpiece, evaporative pattern The process of molding the mold cavity using the mold and the molten metal with the larger specific gravity of the main body melt as the material of the mold body and the main part melt as the material of the main part from the weir below the mold After injecting a predetermined amount into the cavity and a molten metal having a higher specific gravity into the cavity, the disappearance model is vaporized by the heat of the melt, and the coating agent applied to the disappearance model by the gas pressure is While being stuck to the product molding surface of the cavity, the molten metal having the smaller specific gravity of the main body molten metal or the molten metal of the main part is transferred from the weir on the upper side of the mold to the larger specific gravity in the cavity. implanting on top of the molten metal Characterized in that it has.
[0006]
According to the present invention, in order to inject the molten metal having a smaller specific gravity from the molten metal having the higher specific gravity, both molten metals are mixed in the vicinity of the molten metal surface having the larger specific gravity, but separated from the molten metal surface. At the position, both melts are difficult to mix due to the difference in specific gravity. That is, a layer of the main body molten metal, a mixed layer of the main body molten metal and the main part molten metal, and a layer of the main part molten metal are formed in the cavity.
Therefore, it is possible to mold dies in which the material of the mold body and the material of the main part are different by one casting. For this reason, as in the conventional mold manufacturing method in which the mold body and the main part are separately manufactured and assembled, the machining of the mold body to obtain assembly accuracy, the position adjustment of the main part with respect to the mold body, and It is not necessary to fix the main part. Therefore, the labor for manufacturing the mold can be greatly omitted, and the manufacturing cost of the mold can be reduced.
Further, since the molten metal is injected into the cavity while melting the disappearance model, the disappearance model becomes a resistance, and the flow rate of the molten metal at the time of injection is slowed down. For this reason, the mixing range of a main body molten metal and a principal part molten metal becomes narrow, and the mixed layer of both molten metal can be made comparatively thin.
Furthermore, when the molten metal having a smaller specific gravity is poured into the cavity, the mold forming agent applied to the disappearance model by the gas pressure is attached to the product molding surface of the cavity. For this reason, when the molten metal having a smaller specific gravity is poured into the cavity, the molten metal does not directly contact the product molding surface, and casting defects such as sand entrainment can be prevented.
In addition, when molten metal having a high specific gravity is injected into the cavity, the disappearance model gas vaporized by heat covers the molten metal surface, so that no oxide film is formed on the molten metal surface. For this reason, when molten metal with small specific gravity is poured into a cavity, both molten metal becomes easy to mix in the vicinity of a molten metal surface.
[0007]
The mold manufacturing method according to claim 2 is the mold manufacturing method according to claim 1, wherein the temperature of the molten metal having a smaller specific gravity is made higher than the temperature of the molten metal having a larger specific gravity. characterized by increasing the difference in specific gravity between both melt.
Thereby, the mixing range of the main body molten metal and the main part molten metal can be made relatively narrow, and the main body molten metal layer and the main part molten metal layer can be reliably formed.
[0008]
The method for producing a mold according to claim 3 is the method for producing a mold according to claim 1 or 2, wherein a substance that is gasified at a melting temperature is mixed into a molten metal having a smaller specific gravity. by, characterized by increasing the specific gravity difference between the molten metal towards the molten metal and the specific gravity of the person that a smaller specific gravity is large.
Thus, the same operation and effect as those of the invention of the second aspect can be obtained.
[0009]
The mold manufacturing method according to claim 4 is the mold manufacturing method according to any one of claims 1 to 3, wherein after the flow of the molten metal having a larger specific gravity is subsided, Before the molten metal surface solidifies , the molten metal having a smaller specific gravity is injected into the cavity .
[0010]
As described above, since the molten metal having the smaller specific gravity is injected while the molten metal surface having the larger specific gravity is not solidified, both molten metals are surely mixed in the vicinity of the molten metal surface . For this reason, the principal part of a metal mold | die and a metal mold body can be firmly connected.
[0015]
The mold manufacturing method according to claim 5 is the mold manufacturing method according to any one of claims 1 to 4 , wherein the specific gravity is larger before the molten metal having a smaller specific gravity is injected into the cavity. The molten metal is cooled to reduce the fluidity of the molten metal.
According to the present invention, the fluidity of the molten metal having a high specific gravity injected earlier is lowered by cooling. Therefore, the mixing range between the molten metal and the molten metal having a low specific gravity is narrowed, and the mixed layer of both molten metals can be further thinned.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, based on FIGS. 1-6, the manufacturing method of the metal mold | die concerning one embodiment of this invention and the metal mold manufactured by the method are demonstrated. This embodiment utilizes the present invention when manufacturing a press die in a full mold method using a disappearance model. FIG. 1 is a longitudinal sectional view of an essential part of a sand mold 10 used in the present embodiment. It is shown.
[0019]
The sand mold 10 is manufactured by the following procedure. First, the disappearance model 20 having the same shape as the press mold W is manufactured using a disappearance material such as polystyrene foam (see step 101 in FIGS. 1 and 4). Here, as shown in FIG. 5 (A), the press die W is provided with a cutting edge portion Ws (hereinafter referred to as a main portion Ws) for cutting a plate-like workpiece at the upper edge of the die main body Wm. The mold body Wm and the main part Ws are manufactured from different materials. However, the disappearance model 20 is manufactured in a shape in which the mold body Wm and the main part Ws are integrated, that is, in a shape equal to the outer shape of the press mold W.
[0020]
When the vanishing model 20 is manufactured, the lower weir 21 made of the vanishing material is connected to the lower surface 20b of the vanishing model 20. The lower weirs 21 are arranged in a well-balanced manner in a predetermined number so that the molten metal can be uniformly injected into the cavity 14 of the sand mold 10 from below. Further, FC runners 22 made of disappearing material are also connected to the respective lower weirs 21. The FC runner 22 is disposed so as to be substantially parallel to the lower surface 20 b of the disappearance model 20.
Further, an upper weir 23 made of a disappearing material is connected to a position corresponding to the main part Ws of the press die W on the upper surface 20 u of the disappearing model 20. The upper weir 23 is arranged in a well-balanced manner with a predetermined number so that the molten metal can be uniformly injected from above into the upper portion of the cavity 14 for forming the main portion Ws. As a result, it is possible to reduce the amount of the main part molten metal for forming the main part Ws as much as possible. Further, an FCD runner 24 made of disappearing material is connected to each upper weir 23 (see step 102 in FIGS. 1 and 4). The FCD runner 24 is arranged so as to be substantially parallel to the upper surface 20 u of the disappearance model 20.
[0021]
When the upper and lower weirs 21 and 23 and the runners 22 and 24 are set on the disappearance model 20 of the press mold W in this way, a coating agent is applied to the disappearance model 20 and the like (see step 103 in FIG. 4). ). After the coating agent is dried, the disappearance model 20 and the like are stored in the casting frame 12 and sanding is performed (see step 104 in FIG. 4). Here, a pipe-shaped FC gate 26 is connected to the FC runner 22 during sanding, and a pipe-shaped FCD gate 27 is also connected to the FCD runner 24. Sand filling is performed while repeatedly applying vibration so that sand is uniformly filled around the disappearing model 20 and the like.
[0022]
When sanding is thus completed, the first dam 31 is set on the FC gate 26 of the sand mold 10. Further, the second hanging weir 33 is set on the FCD gate 27 of the sand mold 10 (see step 105 in FIG. 4). The first hanging weir 31 is a container for accumulating main body molten metal (hereinafter referred to as FC molten metal) which is a material of the mold main body Wm of the press mold W and injecting the molten metal into the sand mold 10. One stopper 32 is provided. The second hanging weir 33 is a container for accumulating main part molten metal (hereinafter referred to as FCD molten metal) which is a material of the main part Ws of the press mold W and pouring the molten metal into the sand mold 10. Two stoppers 34 are provided.
[0023]
When the first hanging weir 31 and the second hanging weir 33 are set in the sand mold 10, the FC molten metal is supplied to the first hanging weir 31, and the FCD molten metal is further supplied to the second hanging weir 33 to be in a casting standby state. (See step 106 in FIG. 4). Here, the volume ratio of the FC molten metal and the FCD molten metal supplied to the first hanging weir 31 and the second hanging weir 33 is about 2: 1. The FC molten metal is a gray cast iron (FC300) molten metal. C3.0%, Si 1.6%, Mn 0.8%. The temperature of the FC melt is maintained at 1340-1360 ° C.
The FCD melt is a spheroidal graphite cast iron melt. C3.0-4.0%, Si1.5-2.0%, Mn0.5-1.0%, Ni0.2-0.5%, Cu0.4-0.6%, Mo0.2-0.5%, Mg0.01-0.05% . The temperature of the FCD molten metal is maintained at 1350-1400 ° C. T. T. C means the total carbon including compound carbon and free carbon.
[0024]
FIG. 6 is a graph showing a T.S. It is a graph showing the relationship between C component%, Si component%, and specific gravity. According to FIG. The molten metal with a C component of 3.0% has a specific gravity of 6.6. The molten metal with a C component of 3.6% has a specific gravity of 6.45. For this reason, the T.C. of FC molten metal and FCD molten metal. The specific gravity difference due to the C component difference is 0.15. Further, the molten metal with 1.6% Si component has a specific gravity of 7.05, and the molten metal with 2.0% Si component has a specific gravity of 7.0. For this reason, the specific gravity difference resulting from the Si component difference between the FC molten metal and the FCD molten metal is 0.05. For this reason, if other components are ignored, the specific gravity difference between the FC molten metal and the FCD molten metal is about 0.2. That is, the T.C. of FC molten metal and FCD molten metal. Due to the difference between the C component% and the Si component%, the FC molten metal is about 0.2 (g / cm 3) heavier than the FCD molten metal.
[0025]
The FCD melt contains 0.02 to 0.05% of Mg, and the boiling point of Mg is 1100 ° C., so Mg is gasified in the melt. For this reason, many fine gas bubbles exist in the FCD molten metal, and the actual specific gravity of the FCD molten metal is smaller than the specific gravity obtained by calculation due to the influence of the gas.
Furthermore, since the temperature of the FC molten metal is 1340 to 1360 ° C. and the temperature of the FCD molten metal is 1350 to 1400 ° C., the specific gravity difference between the FC molten metal and the FCD molten metal becomes larger than when both the molten metal temperatures are equal. .
[0026]
When the FC melt and the FCD melt are poured into the first dam 31 and the second dam 33, respectively, and the preparation for casting is completed, the first stopper 32 of the first dam 31 is opened and the heavier FC melt becomes FC. It is poured into the sand mold 10 from the gate 26. The molten FC injected from the FC gate 26 melts the FC runner 22 and the lower weir 21 made of the disappearing material and is guided to the cavity 14 formed by the disappearing model 20. Then, the molten FC led to the cavity 14 rises in the cavity 14 while melting the disappearance model 20 from the lower side. At this time, the molten metal is continuously injected without stopping. This is because the pressure of the gas generated when the disappearance model 20 is melted by heat is kept almost constant in the cavity 14. In this way, when the predetermined amount of the molten FC is poured into the sand mold 10 and the molten metal surface reaches the level H (see FIG. 2), the first stopper 32 is closed (see step 107 in FIG. 4).
The level H of the molten metal surface of the FC melt is determined by the positional relationship between the mold body Wm of the press mold W and the main part Ws.
[0027]
When the injection of the FC melt is completed in this way, the FCD melt is then injected.
Here, as described above, the cavity 14 is filled with the gas generated by the dissolution of the disappearance model 20, and a part of the disappearance model 20 and the coating agent applied to the surface by the gas pressure are filled in the cavity 14. Affixed to the product molding surface. However, since the gas pressure decreases with time, the injection of the FCD molten metal must be performed before the gas pressure decreases and the coating agent is peeled off from the product molding surface of the cavity 14.
Further, in order to firmly connect the mold body Wm and the main part Ws, the FC molten metal and the FCD molten metal must be mixed in the vicinity of the molten metal surface of the FC molten metal. For this reason, it is necessary to inject the FCD molten metal before the molten metal surface of the FC molten metal solidifies.
[0028]
On the other hand, the FC molten metal and the FCD molten metal must not be mixed at a position away from the molten metal surface of the FC molten metal. For this reason, it is necessary to inject the FCD melt in a state in which the flow of the FC melt has been subsided. Therefore, in the present embodiment, the injection of the FCD melt is started within 0 to 30 seconds after the injection of the FC melt is completed.
[0029]
When the second stopper 34 of the second dam 33 is opened, the FCD molten metal is poured into the sand mold 10 from the FCD gate 27 to melt the FCD runner 24, the upper weir 23 and the disappeared model 20 made of the disappearing material from above. It is supplied into the cavity 14 (see step 108 in FIG. 4). At this time, since the molten FCD is injected into the cavity 14 while melting the disappearance model 20, the disappearance model 20 becomes a resistance and the flow rate of the FCD melt is reduced. Thereby, the mixed layer of both molten metals formed when the FCD molten metal collides with the molten metal surface of the FC molten metal becomes relatively thin. Here, in the present embodiment, the flow rate during pouring of the FCD melt is set to 100 cm / s or less.
[0030]
When a predetermined amount of FCD molten metal is poured into the sand mold 10 in this way, the cavity 14 of the sand mold 10 is filled with the FC molten metal and the FCD molten metal as shown in FIG. Here, the FC molten metal is heavier than the FCD molten metal, and further, both molten metals are poured into the cavity 14 with a time difference, so that from the lower surface of the cavity 14 to the vicinity of the level H is filled with the FC molten metal, The vicinity of level H is a mixed melt of FC melt and FCD melt, and the vicinity of level H to the upper surface of the cavity 14 is filled with the FCD melt.
That is, the cast iron melt in the cavity 14 is divided into three layers from the top: an FCD melt layer, a mixed layer of FCD melt and FC melt, and an FC melt layer.
[0031]
When the molten metal injection is completed and the molten metal in the sand mold 10 is solidified, the sand mold 10 is disassembled and the internal press mold casting is taken out (see step 109 in FIG. 4). As described above, the molten cast iron in the cavity 14 is separated from the top into three layers of the FCD molten metal layer, the mixed layer, and the FC molten metal layer. From the top, it is composed of three layers: a layer of spheroidal graphite cast iron, a mixed layer of spheroidal graphite cast iron and gray cast iron, and a layer of gray cast iron.
[0032]
After the sand is removed from the press mold casting produced in this way, the surface is cut and finished into a press mold W. At this time, the die body Wm constituting the portion from the lower part of the press die W to the vicinity of the level H is formed by relatively soft gray cast iron (FC300), so that the cutting work is facilitated. On the other hand, the main part Ws constituting from the upper part of the press die W to the vicinity of the level H is formed of hard spheroidal graphite cast iron that can be hardened. It can have equivalent properties. Further, the mixed layer Wc (near level H) between the mold body Wm and the main part Ws of the press mold W has a structure in which gray cast iron and spheroidal graphite cast iron are mixed (CV: worm-like graphite). The mold body Wm and the main part Ws are firmly connected by the mixed layer Wc.
[0033]
Here, FIG. 5B is a micrograph of the metal structure of the main part Ws (casting top) of the press mold W, and FIG. 5C is the metal of the mixed layer Wc (casting center) of the press mold W. A micrograph of the structure, FIG. 5D is a micrograph of the metal structure of the mold main body Wm (lower casting) of the press mold W.
In the present embodiment, since the casting is performed with the main part Ws of the press mold W facing upward, the impurities come to float at the position of the main part Ws. For this reason, when cutting the main part Ws of the press die W, it is necessary to increase a machining allowance. However, in order to reduce impurities in the molten metal and reduce the machining allowance as much as possible, the air permeability of the coating agent is increased to improve gas venting in the cavity, or a low Mg alloy is used, It is also preferable to use a molten metal having a low sulfur content.
[0034]
As described above, according to the mold manufacturing method according to the present embodiment, the press mold W made of a material different from the mold main body Wm and the main part Ws can be integrally formed by casting. Unlike the conventional mold manufacturing method in which the mold body and the main part are separately manufactured and assembled, machining of the mold body, position adjustment of the main part, and fixing of the main part are not required. Therefore, the labor for manufacturing the press mold W can be largely omitted, and the manufacturing cost of the press mold W can be reduced.
[0035]
In addition, since the FC molten metal and the FCD molten metal are temperature controlled so that the specific gravity difference due to the difference in the components of the FC molten metal and the FCD molten metal is further increased, Mg that is gasified at the melting temperature is mixed in the FCD molten metal. The mixing range of FC molten metal and FCD molten metal becomes comparatively narrow, and the mixed layer of both molten metal can be made comparatively thin.
[0036]
In addition, since there is a time difference between the injection of the FC melt and the injection of the FCD melt, the light FCD melt is poured without the heavy FC melt previously poured flowing. At a position away from the molten metal surface, it becomes difficult to mix the FC molten metal and the FCD molten metal. Furthermore, since the FCD molten metal is poured before the molten metal surface of the FC molten metal is solidified, both molten metals are easily mixed in the vicinity of the molten metal surface. For this reason, the mold main body Ws and the main part Ws of the press mold W can be firmly connected.
[0037]
Further, since casting is performed by the full mold method, the molten metal is poured into the cavity while melting the disappearance model 20, and the disappearance model 20 becomes a resistance, and the injection rate of the molten metal is reduced. For this reason, the mixing range of FC molten metal and FCD molten metal becomes narrow, and the mixed layer of both molten metal can be made thin.
Further, when the molten FC is poured into the cavity 14, the gas of the disappearance model 20 vaporized by heat covers the molten metal surface of the FC molten metal, so that no oxide film is formed on the molten metal surface. For this reason, the FC molten metal and the FCD molten metal are easily mixed in the vicinity of the molten metal surface.
[0038]
Furthermore, after the FC molten metal is injected, when the FCD molten metal is injected into the cavity 14, a part of the disappearance model 20 and the coating agent are attached to the product molding surface of the cavity 14 by gas pressure. For this reason, even if the FCD molten metal is injected into the cavity 14, the molten metal does not directly contact the product molding surface, and casting defects due to sand entrainment or the like can be prevented.
[0039]
The sand mold 10 according to the present embodiment is not particularly provided with a molten metal cooling device. However, by installing the cooling device and cooling the FC molten metal previously injected into the cavity 14, the flow of the FC molten metal is reduced. Can be reduced. Accordingly, when the FCD molten metal is injected, the mixing range of the FCD molten metal and the FC molten metal is narrowed, and the mixed layer of both molten metals can be further thinned.
[0040]
Further, in this embodiment, an example in which a heavy FC melt is used as the main body melt and a light FCD melt is used by melting the main part is used. For example, a heavier melt than the main body melt is used for the main part melt, and press It is also possible to perform casting so that the main part Ws of the mold W is on the lower side and the mold body Ws is on the upper side.
In this embodiment, the volume ratio of the FC molten metal to the FCD molten metal is set to about 2: 1. However, it can be set to 1 to 3: 1 depending on the shape of the cavity.
[0041]
【The invention's effect】
According to the present invention, a mold having different materials for the mold main body and the main part can be integrally formed by casting, so that the labor for manufacturing the mold can be largely omitted, and the manufacturing cost of the mold can be reduced. be able to.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a sand mold used in a mold manufacturing method according to an embodiment of the present invention.
FIG. 2 is a diagram showing one step of a mold manufacturing method according to an embodiment of the present invention.
FIG. 3 is a diagram showing one step of a mold manufacturing method according to an embodiment of the present invention.
FIG. 4 is a flowchart showing a mold manufacturing method according to an embodiment of the present invention.
FIG. 5 is a front view (A) of a press mold manufactured by a mold manufacturing method according to an embodiment of the present invention, and a micrograph of a metal structure of a main part (casting upper part) of the press mold ( B), a photomicrograph (C) of the metal structure of the mixed layer (casting center) of the press mold, and a photomicrograph (D) of the metal structure of the die body (bottom of casting) of the press mold.
[Fig. 6] T. of cast iron melt. It is a graph showing the relationship between C component, Si component, and density.
FIG. 7 is a front view of a conventional press die.
[Explanation of symbols]
W Press mold Wm Mold body Wc Mixed layer Ws Main part 10 Sand mold 14 Cavity 20 Disappearance model 21 Lower weir 22 FC runner 23 Upper weir 24 FCD runner

Claims (5)

In the manufacturing method of the mold, the material of the main part that receives large stress when machining the workpiece and the material of the mold body that supports the main part are different.
Molding the mold cavity using the vanishing model;
A step of injecting a predetermined amount of molten metal having a larger specific gravity into the cavity from the lower weir of the mold, either the main body melt that is the material of the mold body or the main part melt that is the material of the main part;
After the molten metal having a higher specific gravity is injected into the cavity, the disappearance model is vaporized by the heat of the molten metal, and the coating agent applied to the disappearance model is adhered to the product molding surface of the cavity by the gas pressure. In between, the step of pouring the molten metal having a smaller specific gravity of the main body molten metal and the main part molten metal from the weir on the upper side of the mold onto the molten metal having the larger specific gravity in the cavity ,
The manufacturing method of the metal mold | die characterized by having. In the manufacturing method of the metal mold according to claim 1,
A mold manufacturing method, wherein the difference in specific gravity between both melts is increased by increasing the temperature of the molten metal having a lower specific gravity than that of the molten metal having a higher specific gravity. In the manufacturing method of the metal mold | die in any one of Claim 1 or Claim 2,
A method for producing a mold characterized by mixing a gas which is gasified at a melting temperature into a molten metal having a lower specific gravity, and increasing a specific gravity difference between a molten metal having a lower specific gravity and a molten metal having a higher specific gravity. . In the manufacturing method of the metal mold according to any one of claims 1 to 3,
A method for producing a mold, characterized by injecting a molten metal having a smaller specific gravity into a cavity before the molten metal surface of the molten metal solidifies after the flow of the molten metal having a larger specific gravity is cured. In the manufacturing method of the metal mold according to claims 1 to 4 ,
A method for producing a mold, comprising: cooling a molten metal having a higher specific gravity to lower the fluidity of the molten metal before pouring the molten metal having a lower specific gravity into the cavity.

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