The disclosure relates to a sprue-bush. More particularly, the disclosure relates to a sprue-bush which is used in a mold.
Technologies supporting “manufacturing” industry in Japan includes a molding technology using molds. The molding technology includes a pressure molding method, an injection molding method, and an extrusion molding method. In these molding methods, the injection molding method is a method for obtaining a molded article from a melt raw resin using a mold for an injection mold.
In the injection molding method, a melt raw resin is injected into a mold cavity 203′ composed of the one of molds (i.e., core side mold) 201′ of an injection mold 200′ and the other of molds (i.e., cavity mold) 202′ thereof (see
As shown in
The flow path for the raw resin 10′ is in a form of a taper to make an ejection of the molded article easier. Specifically, a width dimension W′ of the flow path for the raw resin 10′ gradually increases as it extends from the one of the end portions 10a′ to the other of the end portions 10b′. As shown in
The flow path for the raw resin 10′ in the form of the taper is preferable in view of the ejection of the molded article, however it may not be necessarily preferable in view of the cooling followed by the solidification of the melt raw resin. For example, in a case where the flow path for the raw resin 10′ in the form of the taper has a longer length, it may largely affect the downstream side having a relatively large width dimension W′. Namely, it may make the cooling and subsequent solidification of the melt raw resin difficult. In a case that the cooling and subsequent solidification of the melt raw resin is difficult, it may cause an increase of a necessary time from the injection of the melt raw resin to the ejection of the molded article, which may make a molding cycle longer. Accordingly, as shown in
However, the sprue bush 100′ having the flow path for the cooling media 20′ may cause the following problems (see
In case that the cooling media flow in the flow path for the cooling media 20′, a cooling heat of the cooling media is transmitted to the melt raw resin in the flow path for the raw resin 10′ due to a fact that the sprue-bush 100′ is made of a metal material. In this regard, the melt raw resin in the flow path for the raw resin 10′ tends to be cooled and subsequently solidified more easily at the upstream side 10A′ than the downstream side 10B′ due to the relatively small width dimension of the upstream side 10A′.
In a case that the melt raw resin at the upstream side 10A′ is cooled and subsequently solidified before the cooling and the subsequent solidification of the melt raw resin at the downstream side 10B′, there is a possibility that the flow path for the raw resin 10′ is substantially blocked. In this case, it may make a suitable injection of the raw resin through the flow path for the raw resin 10′ impossible. Thus, it may be impossible to fill the melt raw resin having a predetermined amount into the mold cavity 203′. Therefore, a molded article having a desired shape cannot be finally obtained.
Under these circumstances, the present invention has been created. That is, an object of the present invention is to provide a sprue-bush which is capable of more suitably cooling the melt raw resin in the flow path for the raw resin.
In order to achieve the above object, an embodiment of the present invention provides a sprue-bush comprising a flow path for a raw resin and a flow path for cooling media located around the flow path for the raw resin, wherein the sprue-bush comprises a low heat transfer portion, the low heat transfer portion being located at a local region between an upper side portion of the flow path for the raw resin and the flow path for the cooling media, the low heat transfer portion being in a heat transfer relatively lower than that of a region other than the local region.
In the sprue-bush according to an embodiment of the present invention, it is possible to more suitably cool the melt raw resin in the flow path for the raw resin.
A sprue-bush according to an embodiment of the present invention will be described in more detail with reference to accompanying drawings. It should be noted that a configuration and a dimensional proportion of each of elements in the drawings are merely shown for illustrative purposes, and thus they are not the same as those of each of actual elements.
As shown in
The flow path for the raw resin 10 of the sprue-bush 100 extends from the one of end portions 10a where a melt raw resin is supplied, to the other of end portions 10b which leads into a mold cavity. On a basis of a flow of the melt raw resin at a time of a molding, the one of the end portions 10a corresponds to an “upstream side” end portion and the other of the end portions 10b corresponds to a “downstream side” end portion. In order to make an ejection of a molded article to be obtained by cooling and subsequently solidifying the melt raw resin easier, the flow path for the raw resin 10 is in a form of a taper. More specifically, the flow path for the raw resin 10 is configured such that its width dimension W gradually increases as it extends from the one of the end portions 10a to the other of the end portions 10b. Namely, a width dimension W1 of an upstream side 10A of the flow path for the raw resin 10 is relatively small, whereas a width dimension W2 of a downstream side 10B of the flow path for the raw resin 10 is relatively large.
The flow path for the cooling media 20 of the sprue-bush 100 is a flow path for flowing the cooling media and is a flow path which contributes to a cooling of the melt raw resin existing in the flow path for the raw resin 10. That is, at the time of molding, a temperature of the melt raw resin existing in the flow path for the raw resin 10 is decreased due to the cooling media flowing through the flow path for the cooling media 20. The phrase “cooling media” as used herein refers to a fluid capable of giving a cooling effect to the melt raw resin existing in the flow path for the raw resin 10, the fluid corresponding to cooling water or cooling gas.
The phrase “upstream side of the flow path for the raw resin” as used herein means a portion located on a proximal side with respect to the one of the end portions 10a into which the melt raw resin is supplied. On the other hand, the phrase “downstream side of the flow path for the raw resin” as used herein means a portion located on a distal side with respect to the one of the end portions 10a into which the melt raw resin is supplied. Although a boundary between the upstream side and the downstream side of the flow path for the raw resin is not particularly limited, it is for example “a half-division point of an entire longitudinal dimension of the flow path for the raw resin”. More specifically, “the upstream side of the flow path for the raw resin” corresponds to a region extending from the one of the end portions 10a of the flow path for the raw resin 10 to the “half-division point of the entire longitudinal dimension of the flow path for the raw resin 10”, for example. On the other hand, “the downstream side of the flow path for the raw resin” corresponds to a region extending from the “half-division point of the entire longitudinal dimension of the flow path for the raw resin 10” to the other of the end portions 10b of the flow path for the raw resin 10, for example.
As shown in
The sprue-bush 100 of the present invention comprises the low heat transfer portion 30 between the upstream side 10A of the flow path for the raw resin 10 and the flow path for the cooling media 20, which prevents the cooling heat due to the cooling media in the flow path for the cooling media 20 from transferring to the upstream side 10A. A prevention of the cooling heat-transfer to the upstream side 10A leads to a more suitable prevention of the cooling of the melt raw resin in the upstream side 10A. Therefore, it is possible to prevent an occurrence of a phenomenon that the melt raw resin is cooled and subsequently solidified at the upstream side 10A prior to the cooling and subsequent solidification thereof at the downstream side 10B, and thus a blocking of the flow path for the raw resin 10 can be prevented.
A prevention of the blocking of the flow path for the raw resin 10 allows the melt raw resin to be more suitably injected via the flow path for the raw resin 10. Therefore, the sprue bush 100 of the present invention allows the melt resin having a predetermined amount to be filled in the mold cavity, and thus it is possible to finally obtain a molded article having a desired shape.
Hereinafter, a method for manufacturing the sprue-bush according to an embodiment of the present invention will be described in detail. The sprue-bush 100 according to an embodiment of the present invention can be manufactured using a “selective laser sintering method” as described below. Without being limited to the above method, it is also possible to form only a part of the sprue-bush 100 by the selective laser sintering method and to subject a metal part prepared in advance to be machined to obtain a remaining of the sprue-bush 100, thereby to finally manufacture the sprue-bush 100. The “part of the sprue-bush 100” can include a base part 102 of the sprue-bush or a part of the base part 102, for example (see
The “selective laser sintering method” to be used for manufacturing the sprue-bush is a method which is capable of manufacturing a three-dimensional shaped object by irradiating a powder material with a light beam. The method can produce the three-dimensional shaped object by an alternate repetition of a powder-layer forming and a solidified-layer forming on the basis of the following (i) and (ii):
(i) forming a solidified layer by irradiating a predetermined portion of a powder layer with a light beam, thereby allowing a sintering of the predetermined portion of the powder or a melting and subsequent solidification of the predetermined portion; and
(ii) forming another solidified layer by newly forming a powder layer on the formed solidified layer, followed by similarly irradiating the powder layer with the light beam.
This kind of technology makes it possible to produce the three-dimensional shaped object with its complicated contour shape in a short period of time. The three-dimensional shaped object obtained can be used as a sprue-bush or a part of the sprue-bush in a case where an inorganic powder material (e.g., a metal powder material) is used as the powder material.
Taking a case as an example wherein the metal powder is used as the powder material, and the three-dimensional shaped object produced therefrom is used as the sprue-bush or a part of the sprue-bush, the selective laser sintering method will now be briefly described. As shown in
In order to dispose the flow path for the raw resin 10 and the flow path for the cooling media 20 in the sprue-bush 100 as the three-dimensional shaped object (see
As described above, in a case of the formation of a part of the sprue-bush 100 (e.g., the base portion 102 of the sprue-bush) by the selective laser sintering method, a metal part may be subjected to a machine process using a machine tool to a remaining portion of the sprue-bush (e.g., the flange portion 101 of the sprue bush) comprising a part of the flow path for the raw resin 10 and a part of the flow path for the cooling media 20. As the machine tool, for example, an end mill can be used. The end mill may be a ball end mill having two blades, the ball end mill being composed of a super hard material . Then, a part of the sprue-bush and the remaining part thereof are contacted with each other such that a part of the flow path for the raw resin 10 formed in the part of the sprue-bush and a part of the flow path for the raw resin 10 formed in the remaining part of the sprue-bush are in a connection with each other. Also, a part of the sprue-bush and the remaining part thereof are contacted with each other such that a part of the flow path for the cooling media 20 formed in the part of the sprue-bush and a part of the flow path for the cooling media 20 formed in the remaining part of the sprue-bush are in a connection with each other. Such the contact of the precursors of the sprue-bush with each other allows a desired sprue-bush to be obtained.
Specific embodiments on the low heat transfer portion will be described below.
The low heat transfer portion provided in the sprue-bush mainly has two specific embodiments.
A first specific embodiment relates to an embodiment wherein a hollow portion is applied. In such the embodiment, the low heat transfer portion is composed of a hollow portion. The hollow portion may be used (1) in a vacuum state, (2) as a flow path for heat media for flowing the heat media, or (3) as a space for providing a body of powders.
(1) In a case where the hollow portion is used in a vacuum state, the number of gas molecules transferring heat is low in the hollow portion. Thus, the hollow portion can suitably function as a “heat insulating region”. (2) In a case that the hollow portion is used as the flow path for the heat media, a warm heat arising from the heat media causes a heat transfer due to the cooling media in the flow path for the cooling media to be reduced at a position where the flow path for the heat media is provided and its vicinity. Such the hollow portion can suitably function as a “region where a cooling heat transfer is reduced”. (3) In a case where the hollow portion has the body of the powders therein, the powder particles are brought into a “point” contact with each other and thus a heat transfer of the body of the powders becomes relatively low. Therefore, such the hollow portion can suitably function as the “region where the cooling heat transfer is reduced”.
A second specific embodiment relates to an embodiment wherein a material of the sprue-bush is locally changed.
For example, a sprue-bush according to the second specific embodiment comprises the low heat transfer portion which is made of a porous material. The porous material has a large number of voids therein, which makes it possible to reduce the cooling heat resulting from the cooling media in the flow path for the cooling media. Therefore, the porous material can suitably function as a “region where the cooling heat transfer is reduced”.
According to the present invention, at least one of the above two specific embodiments allows “the low heat transfer portion locally provided between the upper side portion of the flow path for the raw resin and the flow path for the cooling media” to be suitably realized. The above two specific embodiments will be described in detail below.
The sprue-bush 100 according to an embodiment of the present invention comprises the low heat transfer portion which composed of the hollow portion 40 as shown in
Hollow Portion in Vacuum State
The hollow portion 40 may be in a vacuum state (see
The hollow portion 40 does not have to be in a complete vacuum state, and it may include air from an outside. The air has a thermal conductivity smaller than a metal material .
For example, the thermal conductivity of the metal material (e.g., an iron material) at a room temperature is about 80 W·m−1·K−1, whereas the thermal conductivity of air is about 0.02 W·m−1·K−1. Therefore, even if the air intentionally enters the hollow portion, the transfer of the cooling heat arising from the cooling media is prevented due to a presence of the hollow portion 40.
The hollow portion 40 in the vacuum state can be obtained by the following method for example. Firstly, upon the formation of the solidified layer in accordance with the selective laser sintering method, a certain local region is not irradiated with the light beam, and then the powder in the local region is finally removed to form the hollow portion. Without being limited to the above, a local region of the metal part is subjected to the machine process to form the hollow portion.
After forming the hollow portion, a so-called “evacuation” is performed from a communicating portion 45 with the outside to obtain the hollow portion 40 in the vacuum state (see
Hollow Portion as Flow Path for Heat Media
The hollow portion 40 may be a flow path for heat media 40a as shown in
In the sprue-bush 100 comprising the hollow portion 40 as the flow path for the heat media 40a, the cooling media are flowed in the flow path for the cooling media 20, and the heat media are flowed in the flow path for the heat media 40a. At least a part of the flow path for the heat media 40a is located between the upstream side 10A of the flow path for the raw resin 10 and the flow path for the cooling media 20. Thus, a transfer of the cooling heat resulting from the cooling media in flow path for the cooling media 20 is prevented at a region where the flow path for the heat media 40a is provided and a vicinity thereof. As a result, it is possible to prevent the cooling heat from the flow path for the cooling media 20 from transferring to the upstream side 10A of the flow path for the raw resin 10. Thus, it is possible to prevent the occurrence of the phenomenon that the melt raw resin is cooled and subsequently solidified at the upstream side 10A prior to the cooling and subsequent solidification thereof at the downstream side 10B. Therefore, the blocking of the flow path for the raw resin 10 can be more suitably prevented.
The flow path for the heat media 40a can be suitably obtained by a connection of a pipe for heat media to the hollow portion 40, the pipe for the heat media being connected to a source of heat media and including such as a fluid pump.
Hollow Portion Having Filled Body of Powders
In the sprue-bush 100 according to an embodiment of the present invention, a body of powders (i.e., powder-body) may be used. As shown in
In a case where the hollow portion 40 has the body of powders 50 therein, the powder particles in the hollow portion 40 are brought into the “point” contact with each other and thus the heat transfer of the body of the powders becomes relatively low. Thus, the body of the powders 50 allows a transfer of the cooling heat to be reduced, the cooling heat being due to the cooling media in the flow path for the cooling media 20. As a result, it is possible to prevent the cooling heat from transferring from the flow path for the cooling media 20 to the upstream side 10A of the flow path for the raw resin 10. Thus, it is possible to prevent the occurrence of the phenomenon that the melt raw resin is cooled and subsequently solidified at the upstream side 10A prior to the cooling and subsequent solidification thereof at the downstream side 10B. Therefore, the blocking of the flow path for the raw resin 10 can be more suitably prevented.
In a case where the hollow portion 40 has the body of powders 50 therein, it is possible to obtain an effect that a structural strength of the sprue-bush 100 is increased. The hollow portion 40 forms a “space” inside the sprue-bush. Thus, a presence of the hollow portion 40 may be not generally preferable in respect of the structural strength of the sprue-bush 100. In this regard, as shown in
The hollow portion 40 filled with the body of the powders 50 can be obtained by performing the selective laser sintering method. Specifically, upon the formation of the solidified layer in accordance with the selective laser sintering method, a region where the body of the powders is provided is not irradiated with the light beam to make such the region a non-irradiated portion. Then, the powders in the non-irradiated part are not removed and the remaining state of the powders is kept until a completion of manufacturing the sprue-bush. Thus, it is possible to obtain the sprue-bush 100 comprising the hollow part 40 having the body of the powders 50 therein. Without being limited to the above, a certain local region of a metal part is subjected to a machine process to form the hollow portion 40, and then a supply of the powders into the hollow portion 40 is performed to thereby obtain the “hollow portion 40 having the body of the powders 50 therein”.
The sprue-bush 100 according to an embodiment of the present invention comprises the low heat transfer part 30 which is composed of a porous material 60 as shown in
The air substantially exists in the voids of the porous material 60. As described above, the thermal conductivity of the air is lower than that of the metal material . Thus, the porous material 60 in which the air exists allows a transfer of the cooling heat resulting from the cooling media in the flow path for the cooling media 20 to be reduced. As a result, it is possible to prevent the cooling heat from transferring from the flow path for the cooling media 20 to the upstream side 10A of the flow path for the raw resin 10. Thus, it is possible to prevent the occurrence of the phenomenon that the melt raw resin is cooled and subsequently solidified at the upstream side 10A prior to the cooling and subsequent solidification thereof at the downstream side 10B.
The porous material 60 as the low heat transfer portion 30 may be obtained by the selective laser sintering method. Upon the formation of the solidified layer in accordance with the selective laser sintering method, a formation of a region composed of the porous material 60 is possible due to a control of the irradiation conditions of the light beam. More specifically, upon an irradiation of a part of the region to be the solidified layer with the light beam, a reduction of the irradiation energy of the light beam allows a sintered density of such a part to be relatively lower. For example, the sintered density can be set to 40% to 90%. The region of the solidified layer having such a low sintered density can be used as a region of the porous material 60. For example, a lower the irradiation energy of the light beam having about 2 to 3 J/mm2 can make the sintered density about 70 to 80% for example. The formation of the region of the porous material 60 can result from not only (1) the reduction of the irradiation energy of the light beam, but also (2) an increase of a scanning speed of the light beam, (3) a widening of a scanning pitch of the light beam, and (4) an increase of a condensing diameter of the light beam.
The first and second specific embodiments described above each relates to an embodiment on the low heat transfer portion between the upstream side of the flow path for the raw resin flow path and the flow path for the cooling media. In this regard, the following embodiment allows the “heat transfer to the upstream side of the flow path for the raw resin” to be reduced.
Flow Path for Cooling Media with Coating Layer
A sprue-bush 100 shown in
As shown in
Although the sprue-bush according to an embodiment of the present invention has been hereinbefore described, the present invention is not limited to the above embodiment. It will be readily appreciated by the skilled person that various modifications are possible without departing from the scope of the present invention.
The sprue-bush according to an embodiment of the present invention can be used to inject a melt raw resin into a mold cavity composed of a core side and a cavity side in an injection mold.
The present application claims the right of priority of Japanese Patent Application No. 2016-046210 (filed on Mar. 9, 2016, the title of the invention: 37 SPRUE-BUSH”), the disclosure of which is incorporated herein by reference.
Number | Date | Country | Kind |
---|---|---|---|
2016-046210 | Mar 2016 | JP | national |
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/JP2017/000869 | 1/12/2017 | WO | 00 |