Patent Application
20110100581
The present invention relates to a semimolten or semisolid molding method and a molding apparatus.
In the conventional art, a scroll member that has a scroll shaped portion, such as a fixed scroll or a movable scroll of a scroll compressor, is molded by a semimolten or semisolid molding method. For example, a scroll member is cast using a scroll casting apparatus, which is described in Japanese Laid-open Patent Application Publication No. H8-155626.
In such a scroll casting apparatus, when a cavity, which is a casting space inside the forming mold, is filled with molten metal, namely, when it is supplied with melt, the cavity is filled from the circumferential edge of an end plate, which is a flat plate portion of the scroll member (refer to
However, in the semimolten or semisolid molding method using horizontal delivery, namely, when the cavity is filled with semimolten or semisolid cast iron, from the circumferential edge of the end plate, the shape of the pouring gate is widened and, consequently, the cross sectional length (and the circumferential length of the cross section) thereof is enlarged to secure the cross sectional area of the pouring gate needed to fill the scroll shaped portion of the scroll member. As a result, the semimolten or semisolid metal that fills the cavity during molding tends to cool, which can cause problems such as molding failures of the scroll member, for example, misruns in the thin scroll tip part, air inclusions, and cold shuts.
An object of the present invention is to provide a semimolten or semisolid molding method and a molding apparatus that can prevent misruns, air inclusions, and cold shuts during molding.
A semimolten or semisolid molding method according to a first aspect of the present invention is a semimolten or semisolid molding method for casting a molded article, which comprises a flat plate portion and a projected portion that projects from one surface of the flat plate portion, with a semimolten or semisolid metal. This molding method comprises the step of: filling a cavity, which is a casting space of the molded article formed inside a forming mold, with the semimolten or semisolid metal in plate thickness directions of the flat plate portion starting from an other surface on the opposite side of the flat plate portion to a one surface wherefrom the projected portion projects.
Here, because the cavity is filled with the semimolten or semisolid metal in the plate thickness directions of the flat plate portion starting from the other surface, which is on the opposite side of the flat plate portion to the one surface wherefrom the projected portion projects, the entire cavity can be smoothly filled with the semimolten or semisolid metal. As a result, it is possible to prevent misruns, air inclusions, and cold shuts.
A semimolten or semisolid molding method according to a second aspect of the present invention is the molding method according to the first aspect of the present invention, wherein the aspect ratio of a passageway cross section of a runner, which is a passageway for filling the cavity with the semimolten or semisolid metal, is less than 1:3.
Here, because the aspect ratio of the passageway cross section of the runner is less than 1:3, the cross sectional length of the passageway of the runner is reduced. Thereby, it is possible to reduce cooling of the semimolten or semisolid metal at the runner portion, which improves the fluidity of the melt. Consequently, the melt tends not to cool and misruns can be prevented, which improves yield.
A semimolten or semisolid molding method according to a third aspect of the present invention is the molding method according to the first or second aspects of the present invention, and comprises the steps of: inserting an insert or slide mold, which is separate from the forming mold, between the cavity and a runner, which is a passageway for filling the cavity with the semimolten or semisolid metal, from a direction different from the directions in which the runner extends; and subsequently filling the forming mold with the semimolten or semisolid metal.
Here, the insert or slide mold, which is separate from the forming mold, is inserted between the runner and the cavity from a direction different from the directions in which the runner extends, and the forming mold is subsequently filled with the semimolten or semisolid metal; therefore, it is possible not only to extend the runner to the center of the cavity but also to provide a scale trap mechanism along the runner and to effectively prevent the creation of a decarburized layer and the inclusion of oxide scaling. Moreover, after molding, the insert or slide mold can be easily detached from the forming mold without interfering with the runner.
A semimolten or semisolid molding method according to a fourth aspect of the present invention is the molding method according to the first through third aspects of the present invention, wherein the molded article is a scroll member that comprises an end plate, which is the flat plate portion, and a scroll shaped portion, which is the projected portion. The scroll member further comprises a columnar boss that projects toward the other surface on the opposite side of the end plate to the one surface wherefrom the scroll shaped portion projects. The cavity of the forming mold of the scroll member is filled with the semimolten or semisolid metal through a runner, which is a passageway for filling the cavity with the semimolten or semisolid metal, from the boss portion.
Here, filling the cavity starting from the boss of the scroll member makes it possible to smoothly fill the entire cavity with the semimolten or semisolid metal, and thereby to more effectively prevent misruns.
A semimolten or semisolid molding apparatus according to a fifth aspect of the present invention is a semimolten or semisolid molding apparatus for casting a molded article, which comprises a flat plate portion and a projected portion that projects from one surface of the flat plate portion, with a semimolten or semisolid metal. The molding apparatus comprises: a forming mold wherein a cavity, which is a casting space of the molded article, is formed; and an insert or slide mold. The insert or slide mold is disposed between the cavity and a runner in order to form the runner, which is a passageway for filling the cavity with the semimolten or semisolid metal in plate thickness directions of the flat plate portion starting from an other surface on the opposite side of the flat plate portion to a one surface wherefrom the projected portion projects. The insert or slide mold is separate from the forming mold and is inserted from a direction different from the directions in which the runner extends.
Here, the molding apparatus comprises an insert or slide mold, which is separate from the forming mold, that is disposed between the cavity and a runner in order to form the runner, which is a passageway for filling the cavity with the semimolten or semisolid metal in plate thickness directions of the flat plate portion starting from an other surface on the opposite side of the flat plate portion to a one surface wherefrom the projected portion projects; wherein, the insert or slide mold is inserted from a direction different from the directions in which the runner extends; therefore, the runner can be extended to the center of the cavity, which effectively prevents the creation of a decarburized layer and the inclusion of oxide scaling.
According to the first aspect of the present invention, the entire cavity can be smoothly filled with the semimolten or semisolid metal. As a result, it is possible to prevent misruns, air inclusions, and cold shuts.
According to the second aspect of the present invention, it is possible to reduce cooling of the semimolten or semisolid metal at the runner portion, which improves the fluidity of the melt. Consequently, the melt tends not to cool and misruns can be prevented, which improves yield.
According to the third aspect of the present invention, it is possible to extend the runner to the center of the cavity and to provide a scale trap mechanism, which effectively prevents the creation of a decarburized layer and the inclusion of oxide scaling. Moreover, after molding, the insert or slide mold can be easily detached from the forming mold without interfering with the runner.
According to the fourth aspect of the present invention, the entire cavity can be smoothly filled with the semimolten or semisolid metal, and thereby misruns can be prevented more effectively.
According to a fifth aspect of the present invention, the runner can be extended to the center of the cavity and a scale trap structure can be provided, which effectively prevents the creation of a decarburized layer and the inclusion of oxide scaling.
Next, an embodiment of the semimolten or semisolid molding method and the molding apparatus of the present invention will be explained, referencing the drawings.
A semimolten or semisolid molding apparatus 1 (hereinbelow, called a molding apparatus 1) shown in
The molding apparatus 1 comprises a scroll member forming mold 2 (hereinbelow, called a forming mold 2), scroll ejector pins 3, an insert or slide mold 5, a material filling mechanism 6, an ejector pin drive mechanism 7, and a base frame 8.
In the molding apparatus 1, the material filling mechanism 6 fills, while applying pressure, the interior of the forming mold 2 with a semimolten or semisolid metal material C, which is a ferrous semimolten or semisolid metal material, and thereby the scroll member 50 can be molded.
After the scroll member 50 has been molded, a driving means (not shown) pulls one of the molds that constitute the forming mold 2, namely, a movable mold 11, along the base frame 8 away from the other mold, namely, a fixed mold 12 (refer to
The forming mold 2, the scroll ejector pins 3, and the insert or slide mold 5 are described in greater detail in separate sections below.
As shown in
In addition, the molding apparatus 1 further comprises the insert or slide mold 5 in order to form a runner 54, or passageway, for filling a casting space—namely, a cavity 13, which has the shape of the scroll member 50 that is formed when the movable mold 11 and the fixed mold 12 are joined—with the semimolten or semisolid metal material.
The insert or slide mold 5, which is a separate member from the movable mold 11 and the fixed mold 12 of the forming mold 2, is disposed between the cavity 13 and the runner 54 and is detachably attached to the fixed mold 12.
The insert or slide mold 5 is disposed between the cavity 13 and the runner 54 in order to form the runner 54, which is a passageway for filling the cavity 13 with the semimolten or semisolid metal in the plate thickness directions of the end plate 52 starting from a second surface 52b; note that the second surface 52b is on the opposite side of the end plate 52, which is a flat plate portion, to a first surface 52a wherefrom the scroll shaped portion 51, which is a projected portion of the end plate 52, projects.
For example, the slide mold 5 can move reciprocatively along directions different from those in which the runner 54 extends, namely, in the present embodiment, the directions perpendicular to the paper plane in
In addition, a bent part of the runner 54 can be provided with a scale trap in order to eliminate any decarburized layer, oxide scaling, or the like. For example, as shown in
As shown in
As shown in
The movable mold 11 is fixed to a movable platen 21 and moves reciprocatively together with the movable platen 21 on the base frame 8. The fixed mold 12 is fixed to a fixed platen 22 and is stationary on the stage 8.
The scroll ejector pins 3 shown in
After the scroll member 50 has been molded, the scroll ejector pins 3 can eject the scroll member 50 from the movable mold 11 by pressing against a tip 51a of the scroll shaped portion 51 of the scroll member 50.
In the semimolten or semisolid molding method of the present embodiment, the cavity 13, which is the casting space of the scroll member 50—namely, the molded article formed inside the forming mold 2—is filled with the semimolten or semisolid metal in the plate thickness directions of the end plate 52 starting from the second surface 52b, which is on the opposite side of the end plate 52 to the first surface 52a wherefrom the scroll shaped portion 51 projects. Consequently, because the melt is supplied not from the circumferential edge of the end plate 52 but rather from the rear side surface, whereon the scroll shaped portion 51 is not formed, namely, the second surface 52b, it is possible to smoothly fill the entire cavity 13 with the semimolten or semisolid metal and, as a result, to prevent misruns, air inclusions, or cold shuts.
In addition, the scroll member 50 molded in the present embodiment is a movable scroll that comprises the columnar boss 53 that projects from the second surface 52b, which is on the opposite side of the end plate 52 to the first surface 52a wherefrom the scroll shaped portion 51 projects. Accordingly, the semimolten or semisolid metal fills the cavity 13 of the forming mold 2 of the scroll member 50 from the portion of the boss 53 positioned at the center of the end plate 52 and through the runner 54, which is a passageway for filling the cavity 13 with the semimolten or semisolid metal.
Thus, filling the cavity 13 starting from the boss 53 of the scroll member 50 makes it possible to smoothly fill the entire cavity 13 (particularly the entire flat plate shaped groove 13b wherein the end plate 52 is formed) with the semimolten or semisolid metal.
Furthermore, after molding, one end of the runner 54 is connected to the boss 53, and the other end of the runner 54 is connected to the material residuary part 55 on the material filling mechanism 6 side. Accordingly, after molding, the scroll member 50 is removed from the forming mold 2 as shown in
Furthermore, in order to eliminate any decarburized layer, oxide scaling, or the like on the surface of the semimolten or semisolid metal material C immediately after the semimolten or semisolid metal material C comes out of the material filling mechanism 6, the material filling mechanism 6 is disposed spaced apart from, but not immediately behind, the boss 53 by a distance commensurate with a dimension of the runner 54. Thereby, because the scale eliminated from the surface of the semimolten or semisolid metal material C principally accumulates in the scale trap (not shown), which is configured along the material residuary part 55, the runner 54, or the like, contamination of the scroll member 50 by impurities is reduced.
In addition, as shown in
Because the aspect ratio of the passageway cross section of the runner 54 is less than 1:3, the passageway of the runner 54 is not flat but rather has, for example, a somewhat square or circular cross sectional shape. Thereby, the reduced cross sectional length of the passageway of the runner 54 (as well as the circumferential length of the pouring gate cross section) reduces cooling of the semimolten or semisolid metal at the runner 54 portion, which improves the fluidity of the melt.
Furthermore, there is a relation expressed as equivalent hydraulic diameter=4A/L, wherein A is the cross sectional area of the passageway and L is the cross sectional length (or the circumferential length of the pouring gate cross section). Here, the equivalent hydraulic diameter refers to the diameter of a tube of equivalent cross section.
For example, in a concrete example wherein the aspect ratio of the passageway cross section of the runner 54 is less than 1:3, if the passageway cross section of the runner 54 is a square cross section of 30×30 mm (i.e., with an aspect ratio of 1:1), then an equivalent hydraulic diameter D1 is calculated by D1=(4A/L)=(4×30×30)/(4×30)=30 mm, and therefore a passageway equivalent to a passageway with a circular cross section of 30 mm can be secured.
However, in a concrete example wherein the aspect ratio of the passageway cross section of a runner 154 is 1:10-1:7, as shown in a comparative example discussed below (refer to
The aspect ratio of the passageway cross section of the runner 54 should be less than 1:3, and thereby the runner 54 is formed with an easy-to-design rectangular cross section, as shown representatively in
In addition, in the present embodiment, the insert or slide mold 5, which is separate from the forming mold 2, is inserted between the runner 54 and the cavity 13 from a direction different from the directions in which the runner 54 extends, and the forming mold 2 is subsequently filled with the semimolten or semisolid metal. Thus, the insertion of the insert or slide mold 5, which is separate from the forming mold 2, into the fixed mold 12 makes it possible to extend the runner 54 to the center of the cavity 13 (in particular, to the end plate 52 portion), and thereby to effectively prevent misruns, air inclusions, or cold shuts.
Next, the semimolten or semisolid molding method, which uses the molding apparatus 1 of the present embodiment, will be explained, referencing
First, starting from an initial state shown in
Subsequently, as shown in
Next, as shown in
Subsequently, as shown in
Next, as shown in
Next, as shown in
However, if a slide mold is used as the insert or slide mold 5, then, prior to driving the ejector pin drive mechanism 7, the slide mold 5 is opened using a slide mold drive mechanism (not shown) or the like, which is provided to, for example, the movable mold 11, to divide the slide mold 5 in two and move the two parts away from one another along the directions perpendicular to the paper plane in
Next, as shown in
The molded scroll member 50 is cut at the boundary portion between the runner 54 and the boss 53 and separated from the runner 54 and the material residuary part 55. In addition, the insert 5 interposed between the scroll member 50 and the runner 54 is separated therewith.
With regard to the final finishing of the scroll member 50, the scroll member 50 can be surface finished to the dimensions and surface roughness required of the finished article using end milling, wheel mounted grinding, aero lapping, and the like.
Here, as a comparative example shown in
In a molding method wherein the cavity 113 is filled with semimolten or semisolid cast iron in the scroll casting apparatus 101 according to the comparative example, a so-called horizontal delivery method is adopted wherein the cavity 113 is filled with the melt starting from the circumferential edge of the end plate 152.
Furthermore, as in the molding apparatus 1 shown in
In this comparative example, as shown in
As a result, the semimolten or semisolid metal, with which the cavity 113 is filled during molding, tends to cool inside the flat runner 154, whose cross sectional length is large. Consequently, as shown in
Moreover, as shown in
Moreover, because the shape of the runner 154 is also wide, the scroll member 150 cannot be finished with a lathe after the runner 154 is cut from the molded scroll member 150, and therefore machining wherein a cutting tool, such as an end mill, is used to mill along the outer circumference of the discoidal end plate 152 is further required, which in turn increases manufacturing costs.
(1)
In the present embodiment, the cavity 13, which is a casting space of the scroll member 50 that is the molded article formed inside the forming mold 2, is filled with the semimolten or semisolid metal in the plate thickness directions of the end plate 52 starting from the second surface 52b; note that the second surface 52b is on the opposite side of the end plate 52 to the first surface 52a wherefrom the scroll shaped portion 51 projects. Consequently, because the melt is supplied not from the circumferential edge of the end plate 52 but rather from the rear side surface, namely, the second surface 52b, whereon the scroll shaped portion 51 is not formed, the entire cavity 13 can be smoothly filled with the semimolten or semisolid metal, which prevents misruns, air inclusions, and cold shuts.
(2)
In addition, in the present embodiment, the aspect ratio of the passageway cross section of the runner 54, which is a passageway for filling the cavity 13 with the semimolten or semisolid metal, is t1:t2<1:3. Accordingly, the passageway of the runner 54 is not flat but rather has a somewhat square or circular cross sectional shape. Thereby, reducing the cross sectional length of the passageway of the runner 54 (in addition, the circumferential length of the pouring gate cross section) reduces cooling of the semimolten or semisolid metal at the runner 54 portion, which improves the fluidity of the melt. Consequently, the melt tends not to cool, which makes it possible to prevent misruns and improve yield.
In addition, because the cross sectional shape of the runner 54 is not flat but rather is somewhat square or circular, after the runner 54 is cut off of the molded scroll member 50, a lathe can be used to finish that cut portion of the molded scroll member 50, which makes it possible to reduce manufacturing costs.
(3)
In the present embodiment, the insert or slide mold 5, which is separate from the forming mold 2, is inserted between the cavity 13 and the runner 54, which is a passageway for filling the cavity 13 with the semimolten or semisolid metal, from a direction different from the directions in which the runner 54 extends, and subsequently the forming mold 2 is filled with the semimolten or semisolid metal.
Accordingly, because the insert or slide mold 5, which is separate from the forming mold 2, is inserted into the fixed mold 12, the runner 54 can extend to the center of the cavity 13 (in particular, to the end plate 52 portion), which effectively prevents the generation of a decarburized layer, oxide scaling, or the like. Moreover, after molding, the insert or slide mold 5 can be easily detached from the forming mold 2 without interfering with the runner 54.
Moreover, using the insert or slide mold 5 to supply melt from the boss 53 side makes it possible to shorten the cross sectional length of the pouring gate.
(4)
The scroll member 50 molded in the present embodiment is a movable scroll that comprises the columnar boss 53 that projects from the second surface 52b, which is on the opposite side of the end plate 52 to the first surface 52a wherefrom the scroll shaped portion 51 projects. Accordingly, in the molding method according to the present embodiment, the semimolten or semisolid metal fills the cavity 13 of the forming mold 2 of the scroll member 50 from the portion of the boss 53 and through the runner 54. Thus, filling the cavity 13 starting from the boss 53 of the scroll member 50 makes it possible to smoothly fill the entire cavity 13 (particularly the entire flat plate shaped groove 13b wherein the end plate 52 is formed) with the semimolten or semisolid metal, which more effectively prevents molding failures and enables the manufacture of the scroll member 50 with high quality.
(5)
As mentioned above, in the present embodiment, reducing cooling of the semimolten or semisolid metal at the runner 54 portion further improves the fluidity of the melt; moreover, viewed from the direction in which the cavity 13 is filled, it is possible to fill the cavity 13 from the rear surface side of the center part of the scroll shaped portion 51 of the scroll member 50 toward the radial directions.
For these reasons, it is possible to eliminate misruns in the tip part of the scroll shaped portion 51 of the scroll member 50. In addition, it is possible to eliminate air inclusions as well as to prevent cold shuts.
Moreover, after the runner 54 and the material residuary part 55 are cut off from the molded scroll member 50, the scroll member 50 can be easily finished to its article shape using a lathe, which also makes it possible to reduce the cost of materials.
Furthermore, the present embodiment explained an exemplary case of the scroll member 50 that comprises the scroll shaped portion 51, the end plate 52, and the boss 53, but the shape of the cavity 13 of the molding apparatus 1 may be suitably modified to form a fixed scroll or some other cast article.
Furthermore, in the present embodiment, to eliminate any scale from the surface of the semimolten or semisolid metal material C immediately after the semimolten or semisolid metal material C comes out of the material filling mechanism 6, the material filling mechanism 6 is disposed spaced apart from, but not immediately behind, the boss 53 by a distance commensurate with a dimension of the runner 54, but the present invention is not limited thereto.
As a modified example, the runner 54 may be omitted and the boss 53 may be filled directly and from immediately behind with semisolid metal material and the like. For example, in the case of semisolid molding or semimolten molding that is heated in a vacuum or a nitrogen atmosphere, hardly any oxide scaling is generated, and consequently there is no need for a contamination prevention measure for preventing contamination of the molded article. Therefore, there is no need for a scale trap, such as the material residuary part 55, and molding can be performed without the runner 54. Eliminating the need for the runner 54 consequently improves the yield of the scroll member 50. In addition, the mold configuration can also be simplified.
The present invention can be adapted to a semimolten or semisolid molding method and a molding apparatus.
In addition, the present invention can also be adapted to the molding of a fixed scroll, a rotary front head, and the like.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-169599 | Jun 2008 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2009/002863 | 6/23/2009 | WO | 00 | 12/20/2010 |
