WO2012101824A1

WO2012101824A1 - Evaporative pattern for casting, and cast article

Info

Publication number: WO2012101824A1
Application number: PCT/JP2011/051819
Authority: WO
Inventors: 祐美小林
Original assignee: トヨタ自動車株式会社
Priority date: 2011-01-28
Filing date: 2011-01-28
Publication date: 2012-08-02
Also published as: CN103338877A; JP5445680B2; JPWO2012101824A1; US20130291463A1

Abstract

Provided is an evaporative pattern which has high strength. An evaporative pattern (102) is a pattern for evaporative casting. The evaporative pattern (102) is obtained by burying a reinforcing member (30), which is formed of a material that is not evaporated by the heat of a melt, in a joint (114) which is formed of a material that is evaporated by the heat of the melt. A typical evaporative material is polystyrene foam, and the polystyrene foam is low in strength. The strength of the evaporative pattern (102) is improved by burying a reinforcing member in the evaporative pattern (102) that is formed of polystyrene foam, said reinforcing member being formed of a material that has higher strength than the evaporative material.

Description

Disappearance models and castings for casting

The present invention relates to a casting disappearance model (evaporative pattern) and a cast structure using the disappearance model.

Extinction model casting is a kind of casting method and is also called lost foam casting or full mold casting. This method is outlined as follows. First, a pattern is made of a material that disappears due to the heat of the molten metal. The model is called the disappearance model. Next, make a sand mold in which the disappearance model is embedded. Pour molten metal into the sand mold cavity. Here, the “cavity” means a space occupied by the disappearance model. When the molten metal is poured, the disappearance model disappears due to the heat of the melt, and the space occupied by the disappearance model is filled with the melt. After the molten metal cools and solidifies, if the sand mold is broken, a cast structure with exactly the same shape as the disappeared model is completed. As the disappearing material, typically, polystyrene foam or wax is used.

Extinction material has the property of being weak because it has the property of disappearing with the heat of the molten metal. That is, the strength of the conventional disappearance model is not high. Therefore, for example, Patent Document 1 proposes that a disk-shaped reinforcing member is attached to a hollow space inside a pipe of a pipe-shaped disappearance model. In patent document 1, the vanishing model which attached the reinforcement member is embedded in a sand mold. The reinforcing member is provided with a through hole in the axial direction, and sand enters the pipe through the through hole. The reinforcing member is removed after the cast product is completed.

JP 7-22301 A

In the technique of Patent Document 1, a reinforcing member is embedded in sand in addition to the disappearance model. Therefore, although it has a through hole for passing sand, the back side of the reinforcing member is hardly filled with sand. If the sand around the vanishing model is not sufficiently filled, a desired casting may not be obtained. Therefore, it is necessary to check whether or not the back side of the reinforcing member is sufficiently filled with sand. Moreover, the technique of patent document 1 is not applicable to shapes other than a pipe. The present invention can be applied to shapes other than pipes, and provides a technique that compensates for the lack of strength of the disappearance model without the need to embed a reinforcing member separate from the disappearance model in the sand mold.

The technology disclosed in this specification embeds a reinforcing member in the disappearance model. That is, the strength of the disappearance model itself is improved. This eliminates the need to embed a member other than the disappearance model in the sand mold as in the technique of Patent Document 1. In addition, this method can be applied to any shape of disappearance model. The reinforcing member is made of a material that does not disappear by the heat of the molten metal. Typically, the reinforcing member is made of steel, titanium or other high strength metal.

In addition, in the novel technique disclosed in this specification, the reinforcing member remains inside the cast product. That is, the reinforcing member not only improves the strength of the disappearance model, but also improves the strength of the cast product. The reinforcing member is preferably made of a material having a higher strength than the casting material.

In another aspect of the technology disclosed in this specification, the entire reinforcing member is covered with a vanishing material. This means that a space through which the molten metal flows is secured around the reinforcing member.

In yet another aspect of the technology disclosed in this specification, a wire extends from the reinforcing member to the outside of the disappearance model. The exposed portion of the wire is secured by the mold sand. That is, the reinforcing member is fixed to the sand mold through the wire. When the above wire is used, even if the molten metal is poured and the disappearing material disappears, the reinforcing member is fixed by the wire, so that the reinforcing member does not move. In the disappearance model employing the wire, the reinforcing member can be arranged at a desired position inside the casting.

The technology disclosed in this specification also provides a new cast product. The cast product is a cast product cast by the above disappearance model. That is, the cast product is characterized in that a reinforcing member made of a metal different from the cast material is embedded therein. As described above, the reinforcing member is preferably made of a material having higher strength than the casting material. In this technique, the casting material is preferably iron. That is, one cast product disclosed in this specification is a cast iron structure in which a reinforcing member having higher strength than iron is embedded.

In one aspect of the above cast product, the plurality of rod-shaped members may include a frame having a ramen structure, a truss structure, or a structure in which the ramen structure and the truss structure are combined. Further, in the cast product, a reinforcing member may be embedded in the joint portion of the frame. In the following, for simplicity of explanation, “a structure composed of a plurality of rod-shaped members and a truss structure, a ramen structure, or a structure in which trusses and ramen are mixed” is simply referred to as “framework structure (framework). Structure ”). In the framework structure, since a large load is applied to the joint portion, if the reinforcing member is embedded in the joint portion, the strength of the entire structure can be increased.

A schematic side view of a press machine is shown. The top view of a metal mold | die (disappearance model) is shown. A side view of the mold (disappearance model) is shown. The enlarged view of the joint part of a vanishing model is shown. The enlarged view of the joint part of the vanishing model of a modification is shown. Furthermore, the enlarged view of the joint part of the vanishing model of another modification is shown.

First, the object to be cast with the vanishing model of the example will be described. In the present embodiment, a die for machine press (a die for machine press) is a target cast product. To help understanding, first, an example of using a mechanical press mold will be described. FIG. 1 is a schematic side view of a press machine 50 including dies 2 and 42. FIG. 2A is a plan view of the mold 2, and FIG. 2B is a side view of the mold 2. In FIG. 2B, a mold 42 corresponding to the mold 2 is also illustrated. The mold 2 is fixed to the bolster 51, and the mold 42 is fixed to the slider 52. The slider 52 is moved up and down by the actuator 55 while being guided by the column 53.

The mold 2 has a design block 20, an alignment block 24, and a support block 26. The design block 20 has a design surface 20a for transferring the target shape to the work board. The mold 2 in this example is a mold for press-forming an automobile fender. The design surface 20a is formed in a fender shape. The alignment blocks 24 are located at the four corners of the mold 2. Note that in the figure, only one alignment block is labeled 24 and the other alignment blocks are omitted.

When the work plate W is sandwiched between the design block 20 of the mold 2 and the design block 40 of the mold 42 and the actuator 55 lowers the slider 52 and applies a load to the work plate W, the work plate W becomes the shape of the design surface 20a. Deform. That is, the shape of the design surface 20a is transferred to the work plate W.

When aligning the mold 2 and the mold 42, the guide pin 25 of the mold 2 is fitted into the guide bush 45 of the mold 42, and the positions of the mold 2 and the mold 42 are aligned. That is, the positions of the design surface 20a of the mold 2 and the design surface 40a of the mold 42 are matched. The guide pin 25 is provided on the alignment block 24. As shown in FIG. 2A, the alignment block 24 is arranged at the four corners of the mold 2 so as to surround the design block 20. By disposing the alignment blocks 24 at the four corners of the design block 20, the relative positions of the design surface 20a of the mold 2 and the design surface 40a of the mold 42 can be accurately determined.

The support block 26 is a block for attaching various tools using a press load. The types of tools include, for example, a bending tool that rounds the end of the workpiece, and a punch tool that opens a through hole in the horizontal direction in the workpiece. A support block 46 corresponding to the support block 26 is attached to the mold 42. The tool disposed between the tool blocks 26 and 46 operates the tool by using a load when the support blocks 26 and 46 approach each other as a driving force.

The design block 20, the alignment block 24, and the support block 26 are connected to each other by a plurality of rods 12 (bar-shaped members). The connecting portion between the rods is referred to as “joint 14”. It should be noted that in the figure, only a few rods and joints are labeled, and the other rods and joints are omitted. The plurality of rods 12 are combined vertically, horizontally, and obliquely to form the frame 10. When the lattice window surrounded by the plurality of rods 12 is rectangular, the rods 12 constitute a ramen structure. When the lattice window surrounded by the plurality of rods 12 is a triangular portion, the rods 12 constitute a truss structure. That is, the frame 10 has the framework structure described above. The truss structure means a framework structure in which only an axial force acts on the rod and no moment acts, and the ramen structure means a framework structure in which both an axial force and a moment act on the rod. Since both the ramen structure and the truss structure are composed only of rods, the overall structure has moderate flexibility while having high strength.

The mold 2 is a cast product made by full mold casting or lost foam casting. As will be described in detail later, a reinforcing material made of a metal having higher strength than the cast material is embedded in the joint 14 of the mold 2.

As shown in FIG. 2A, the design block 20 is supported by the rod 12 from four directions when viewed in plan. The design block 20 is also supported from the back surface by the rod 12 arranged in a vertical direction. Since the design block 20 is supported by the rod 12 on the four sides and the back surface, the design block 20 can be moved flexibly when a load is received. That is, when an uneven press load is applied, the design block 20 moves slightly so that the distribution of the press load becomes uniform. Such a slight movement eliminates the bias of the press load. The entire mold 2 is accurately determined relative to the mold 42 by the alignment blocks 24 at the four corners. On the other hand, since the design block 20 is supported by the rod 12 on all sides, the design block 20 moves slightly so as to eliminate the unevenness of the press load. Since the biased press load is not concentrated on the design surface 20a, the wear of the mold is suppressed and high work forming accuracy is maintained.

The rigidity of the design block 20 is higher than the rigidity of the frame 10 assembled by the rod 12. Further, the rigidity of the alignment block 24 is higher than the rigidity of the frame 10. Therefore, when the press load is applied, the deformation amount of the design block 20 and the alignment block 24 is small compared to the deformation amount of the frame 10. In other words, the entire frame 10 is deformed, but the deformation of the design block 20 and the deformation of the alignment block 24 are suppressed. Since the deformation of the design block 20 itself is suppressed, high work forming accuracy can be maintained.

The mold 2 is made by vanishing model casting (full mold casting or lost foam casting). Therefore, a disappearance model having the same shape as the mold 2 shown in FIGS. 2A and 2B is required. Hereinafter, the disappearance model having the same shape as the mold 2 in FIGS. 2A and 2B may be referred to as the disappearance model 102. Further, in the following, the disappearance model parts corresponding to the respective parts of the mold 2 are represented by three-digit numbers including a two-digit number indicating the parts of the mold 2. For example, the number 112 is assigned to the vanishing rod corresponding to the rod 12 of the mold 2. The vanishing model 102 is formed of a vanishing material that disappears due to the heat of the molten metal. The evanescent material is typically a polystyrene foam.

消失 Large size disappearance model is easy to bend. A mold 2 for molding an automobile fender has a size of several meters in length and width. If the disappearance model 102 having such a size is made of foamed polystyrene, it is very easy to bend. In particular, the mold 2 in FIGS. 2A and 2B has a frame 10 including a number of rods 12. The diameter of the rod 12 is several tens of centimeters. If a frame 10 of several meters is made of foamed polystyrene, it is fragile. In particular, the joint 14 is easily broken. Typically, there is a risk of breakage when the lost model is transported or embedded in a sand mold. Therefore, in the technique of this embodiment, a reinforcing member is embedded in the disappearance model 102.

FIG. 3 shows an enlarged view of the joint portion of the disappearance model 102. FIG. 3 shows a vanishing model joint 114 in which four vanishing model rods 112 are connected. The joint part of FIG. 3 appears in various parts of the disappearance model 102. In the vanishing model 102, there are joints to which a number of rods other than four are connected, but the same as in FIG.

The steel reinforcing member 30 is embedded in the joint 114. The reinforcing member 30 extends through the joint 114 so as to connect the ends of the adjacent rods 112. The relative position of the adjacent rods 112 at the joint 114 is maintained by the reinforcing member 30. That is, the reinforcing member 30 improves the strength of the disappearance model 102.

The rod is also connected to the design block and alignment block of the disappearance model 102. The reinforcing member 30 is also embedded in the connecting portion between the block and the rod. That is, the reinforcing member 30 is embedded in various places of the disappearance model 102. The reinforcing member 30 is completely covered with a disappearing material. In other words, when the vanishing model is buried in the sand mold, a passage for the molten metal is always ensured between the sand and the reinforcing member. Therefore, when the molten metal is poured into the sand mold, the molten metal is not blocked by the reinforcing member 30, and the molten metal flows over the reinforcing member 30.

The casting using the vanishing model 102 will be described. First, a sand mold in which the disappearance model 102 (or the disappearance model 202 or 302) having the shape shown in FIGS. 2A and 2B is buried is formed. Next, molten metal (cast iron) is poured into the sand mold cavity. The cavity means a space occupied by the disappearance model 102. The disappearance model 102 is melted by the heat of the molten metal, and the space occupied by the disappearance model 102 is filled with the molten metal. The periphery of the reinforcing member 30 is also filled with the molten metal. Here, the normal temperature reinforcing member 30 promotes cooling of the molten metal. The faster the cooling rate, the higher the hardness of the cast product. That is, embedding the reinforcing member 30 has an advantage of increasing the strength of the cast product. Cast iron in particular is brittle (not high toughness). Therefore, the strength against the pulling force is not particularly high. By making the reinforcing member with a material having high toughness, for example, a general structural rolled steel (JIS standard, SS400, SS490, SS540, etc.), the toughness of the entire cast product can be ensured.

After the molten metal has cooled and solidified, the sand mold is removed, and a cast product having the same shape as the disappearing model 102, that is, the mold 2 is completed. The finished mold 2 has a reinforcing member 30 embedded in the joint 14. More specifically, in the mold 2, the plurality of rods 12 include a frame 10 having a ramen structure, a truss structure, or a combination of a ramen structure and a truss structure, and a reinforcing member 30 is attached to the joint 14 of the frame 10. Embedded. The reinforcing member 30 reinforces the disappearance model, and further reinforces the mold 2 that is a cast product.

FIG. 4 shows a modification of the disappearance model 102. In the vanishing model 202 of FIG. 4, a metal wire 234 extends from the reinforcing member 230 completely covered with the vanishing material to the outside of the vanishing model 202. In other words, the vanishing model 202 includes a wire 234 having one end fixed to the reinforcing member 230 and the other end exposed from the vanishing model 202. When the vanishing model 202 is buried in a sand mold, the end of the wire 234 is fixed to the sand mold. That is, the reinforcing member 230 is directly fixed to the sand mold via the wire 234. Therefore, the reinforcing member 230 does not move when the disappearance model 202 is melted by the heat of the molten metal. Therefore, the reinforcing member 230 can be disposed at an accurate position inside the cast product.

The disappearance model may be made of multiple types of disappearance materials. For example, the rod may be made of paper pipe and the joint part may be made of foamed polystyrene. FIG. 5 shows an enlarged view of the joint portion of such a disappearance model 302. Note that the vanishing model 302 has many joints, some or all of which have the same structure as in FIG. In this vanishing model 302, the joint 314 is made of foamed polystyrene. A steel reinforcing member 30 is embedded in the joint 314. The joints are connected by a paper pipe 312. In this specification, it should be noted that the paper pipe 312 is a kind of rod that connects between two adjacent joints. The joint 314 and the paper pipe 312 are connected by an adhesive. This vanishing model 302 uses a paper pipe 312 as a rod constituting the frame. The vanishing model 302 has an advantage that the molten metal flows well when the molten metal is poured into the sand mold.

In the disappearance model of the embodiment, a reinforcing member is embedded in the joint portion of the frame composed of rods. The place where the reinforcing member is embedded is not limited to the joint. For example, a reinforcing member may be embedded in the design block 20 or the alignment block 24. The reinforcing member embedded in the disappearance model may be any metal that does not melt or burn with the heat of the molten metal. The reinforcing member may be made of a metal such as steel, titanium, or tungsten. The supplementary member is preferably made of a material having higher strength than the cast material.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

2: Mold 10: Frame 12: Rod 14: Joint 20: Design block 20a: Design surface 24: Positioning block 25: Guide pin 30: Support block 50: Press machine 51: Bolster 52: Slider 53: Strut 55: Actuator 102: Disappearance model 112: Disappearance model rod 114: Disappearance model joint

Claims

Disappearance model for casting, characterized in that a reinforcing member made of a material that does not disappear due to the heat of the molten metal is embedded inside the model made of a material that disappears due to the heat of the molten metal .
The vanishing model according to claim 1, wherein the entire reinforcing member is covered with a vanishing material.
3. The vanishing model according to claim 1, wherein a wire extends from the reinforcing member to the outside of the vanishing model.
A cast product cast by the vanishing model according to any one of claims 1 to 3, wherein a reinforcing member made of a metal different from the cast material is embedded in the cast material. Cast product.
The cast product includes a frame in which a plurality of rod-shaped members have a ramen structure, a truss structure, or a combination of a ramen structure and a truss structure, and the reinforcing member is embedded in a joint portion of the frame. The cast product according to claim 4, wherein the cast product is characterized.