Mold of resin body and resin body

This application is based upon and claims the benefit of priority from Japanese patent application No. 2018-048281, filed on Mar. 15, 2018, the disclosure of which is incorporated herein in its entirety by reference.

The present disclosure relates to a mold of a resin body and a resin body.

There is a resin body that includes a resin base material and a foamed resin part provided on the resin base material. After a molten resin is molded to form a resin base material, a foamed resin is filled into a mold and foamed inside the mold, whereby the foamed resin part is formed. One example of a method of manufacturing a resin body is disclosed in Japanese Unexamined Patent Application Publication No. H07-080885.

The present inventors have found the following problems.

In the method of manufacturing the resin body described above, a mold for forming a resin base material and a mold for forming a foamed resin part are often used. Therefore, there is a room for reducing the manufacturing cost.

Incidentally, there is a mold for a resin base material including a core that can come close to or is separated from one mold and is slidably provided on another mold. It may be possible to sequentially perform formation of the resin base material and formation of the foamed resin part using just one mold for a resin base material. When this mold for the resin base material is used, it is possible that the mold may be distorted due to heat given by resin, which prevents the core from sliding. Therefore, there is a room for reducing the manufacturing cost of the resin body.

Molds 91 and 92 shown in FIG. 18 are specific examples of the mold for the resin base material. The mold 91 is arranged so as to be opposed to the mold 92 or to be pressed against it. A core 93 is slidably provided inside the mold 92 and can come close to or be away from the mold 91 . As shown in FIG. 19 , when the mold 92 is deformed, the mold 92 may mechanically interfere with the core 93 , which may prevent the core 93 from sliding.

The present disclosure aims to reduce the cost of manufacturing a resin body including a resin base material and a foamed resin part provided on the resin base material.

A mold of a resin body according to the present disclosure is a mold of a resin body including

a resin base material molding die part for molding a resin base material, the mold of the resin body including:

a sliding part capable of sliding inside a foamed resin part molding cavity that communicates with a resin base material molding cavity of the resin base material molding die part, in which

the sliding part is swingably floated in a direction perpendicular to a sliding surface on which the sliding part slides,

in the process of molding the resin base material, the sliding part blocks an opening part that communicates from the resin base material molding cavity to the foamed resin part molding cavity, and

in the process of molding the foamed resin part, after a foamed resin material is filled into the foamed resin part molding cavity, the sliding part is separated from the resin base material molding cavity, thereby increasing a filling space that can be filled with the foamed resin material.

According to the aforementioned structure, the sliding part is swingably floated, which enables the sliding part to slide even when the mold of the resin body is distorted due to heat given by the resin material. Therefore, it is possible to provide a mold capable of integrally molding the foamed resin part and the resin base material and molding the resin body. The foamed resin part and the resin base material can be integrally molded and the resin body can be molded using only one mold, without using a plurality of molds. It is therefore possible to reduce the cost of manufacturing the resin body including the resin base material and the foamed resin part provided on the resin base material.

Further, a recessed part may be provided on a distal end surface of the sliding part on a side of the resin base material molding cavity.

According to the aforementioned structure, the recessed part is provided on the distal end surface of the sliding part on the side of the resin base material molding cavity. Therefore, in the process of molding the foamed resin part, when the foamed resin is filled into the foamed resin part molding cavity, the size of the contact area of the foamed resin part with the sliding part can be increased. Since it is possible to prevent the foamed resin part from being away from the sliding part, it is therefore possible to mold the foamed resin part with a high precision.

Further, a resin body according to the present disclosure is a resin body including a resin base material and a foamed resin part, in which

the foamed resin part includes a foamed resin body provided on the resin base material and a protruding part having a foaming ratio lower than that of the foamed resin body while covering the foamed resin body, the protruding part is protruded to a side opposite to the side of the resin base material in the foamed resin part, the resin base material includes a base material protruding part in at least a part of an interface between the resin base material and the foamed resin body, and the base material protruding part is protruded toward the inside of the foamed resin body.

According to the aforementioned structure, in the process of molding the foamed resin part, when the foamed resin is filled into the foamed resin part molding cavity of the mold, the size of the contact area of the foamed resin part with the mold can be increased. Accordingly, since it is possible to prevent the foamed resin part from being away from the sliding part of the mold, it is therefore possible to mold the foamed resin part with a high precision. Further, using the mold of the resin body according to the present disclosure described above, the resin base material and the foamed resin part can be integrally molded. That is, this integral molding can be performed using only one mold, without using a plurality of molds. It is therefore possible to reduce the cost of manufacturing the resin body including the resin base material and the foamed resin part provided on the resin base material.

According to the present disclosure, it is possible to reduce the cost of manufacturing the resin body including the resin base material and the foamed resin part provided on the resin base material.

The above and other objects, features and advantages of the present disclosure will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not to be considered as limiting the present disclosure.

FIG. 1 is a schematic cross-sectional view of a mold of a resin body according to a first embodiment;

FIG. 2 is an exploded perspective view of a movable die of the mold of the resin body according to the first embodiment;

FIG. 3 is an exploded perspective view of a core of the mold of the resin body according to the first embodiment;

FIG. 4 is an xz cross sectional view of a divided core 31 c and other peripheral structures;

FIG. 5 is a view showing one process of a method of manufacturing the resin body according to the first embodiment;

FIG. 6 is a view showing one process of the method of manufacturing the resin body according to the first embodiment;

FIG. 7 is a view showing one process of the method of manufacturing the resin body according to the first embodiment;

FIG. 8 is a view showing one process of the method of manufacturing the resin body according to the first embodiment;

FIG. 9 is a view showing one process of the method of manufacturing the resin body according to the first embodiment;

FIG. 10 is a perspective view showing one example of the resin body according to the first embodiment;

FIG. 11 is a schematic view showing operations of the core of the mold of the resin body according to the first embodiment;

FIG. 12 is a schematic view showing an xz cross section of a plate part 31 cb;

FIG. 13 is a view showing one process of one modified example of the method of manufacturing the resin body according to the first embodiment;

FIG. 14 is a view showing one process of one modified example of the method of manufacturing the resin body according to the first embodiment;

FIG. 15 is a view showing one process of one modified example of the method of manufacturing the resin body according to the first embodiment;

FIG. 16 is a view showing one process of one modified example of the method of manufacturing the resin body according to the first embodiment;

FIG. 17 is a schematic cross-sectional view showing one modified example of the resin body according to the first embodiment;

FIG. 18 is a schematic cross-sectional view of main parts of a mold according to a problem to be solved by the present disclosure; and

FIG. 19 is a schematic cross-sectional view of the main parts of the mold according to the problem to be solved by the present disclosure.

The specific embodiment to which the invention is applied will be described hereinafter in detail with reference to the drawings. It should be noted, however, that the invention is not limited to the following embodiment. Besides, the following description and drawings are simplified as appropriate for the sake of clarification of explanation. In FIGS. 1-19 , a right-handed three-dimensional xyz orthogonal coordinate system is specified. Incidentally, as a matter of course, the right-handed xyz-coordinate system shown in FIG. 1 and the other drawings is used for the sake of convenience to illustrate a positional relationship among components. In general, as is common among the drawings, a positive direction along a z-axis is a vertically upward direction, and an xy-plane is a horizontal plane.

First Embodiment

Referring to FIGS. 1-4 , a mold of a resin body according to a first embodiment will be explained. FIG. 1 is a schematic cross-sectional view of the mold of the resin body according to the first embodiment. FIG. 2 is an exploded perspective view of a movable die of the mold of the resin body according to the first embodiment. FIG. 3 is an exploded perspective view of a core of the mold of the resin body according to the first embodiment. FIG. 4 is an xz cross sectional view of a divided core 31 c and other peripheral structures.

As shown in FIG. 1 , a mold 10 includes a fixed die 1 and a movable die 2 . The fixed die 1 and the movable die 2 may each be referred to as a resin base material molding die part. The mold 10 can be used along with an injection molding machine (not shown) and the like in order to mold the resin body.

The fixed die 1 is held at a predetermined position by an injection molding machine or the like. The fixed die 1 includes an inflow hole 1 a and a resin base material molding surface 1 b . A molten resin can be made to flow into the inflow hole 1 a from a resin base material molding injection nozzle 4 . The resin base material molding surface 1 b is continuous with the inner wall surface of the inflow hole 1 a.

The movable die 2 is held by an injection molding machine or the like in such a way that the movable die 2 can be pressed against or separated from the fixed die 1 . As shown in FIG. 2 , the movable die 2 includes a resin base material molding surface 2 a and a sliding part holding hole 2 b . The sliding part holding hole 2 b includes holes 2 c and 2 d that slidably hold the sliding part 3 . The hole 2 d communicates with the hole 2 c . The hole 2 c is preferably thicker than the hole 2 d . The hole 2 c preferably has a cross-sectional area lager than that of the hole 2 d.

As shown in FIG. 1 , when the movable die 2 is pressed against the fixed die 1 , a resin base material molding cavity C 1 is formed between the resin base material molding surface 2 a and the resin base material molding surface 1 b . Further, when the distal end of the sliding part 3 is separated from the fixed die 1 while the movable die 2 is kept to be pressed against the fixed die 1 , a foamed resin part molding cavity C 2 is formed in the hole 2 d . The foamed resin part molding cavity C 2 communicates with the resin base material molding cavity C 1 . The molten resin is made to flow into the foamed resin part molding cavity C 2 from a foamed resin part molding injection nozzle 5 through an inflow hole 2 e.

As shown in FIG. 3 , the sliding part 3 includes a core 31 , a core holder 32 , and a stopping plate 33 . The core 31 preferably includes a plurality of divided cores. This is because, when the core 31 includes a plurality of divided cores, even when the core 31 is distorted and deformed by heat, the core 31 is not likely to mechanically interfere with the core holder 32 and the stopping plate 33 . One example of the core 31 includes a plurality of divided cores 31 a , 31 b , 31 c , 31 d , and 31 e.

One example of the divided core 31 a includes a base part 31 aa and a plate part 31 ab that is extended from the base part 31 aa . The cross-sectional area of the base part 31 aa is larger than that of the plate part 31 ab . In a similar way, one example of the divided core 31 b includes a base part 31 ba and a plate part 31 bb , one example of the divided core 31 c includes a base part 31 ca and a plate part 31 cb , and one example of the divided core 31 d includes a base part 31 da and a plate part 31 db . The plate parts 31 bb , 31 cb , and 31 db respectively extend from the base parts 31 ba , 31 ca , and 31 da.

As shown in FIGS. 2 and 3 , the core holder 32 includes a hole 32 a that can hold the plurality of divided cores 31 a - 31 e . The stopping plate 33 is fitted into the side opposite to the hole 32 a in the core holder 32 while the plates 31 ab - 31 eb of the divided cores 31 a - 31 e are kept to be protruded from the hole 32 a . When the hole 32 a has a cross-sectional shape that is extended in the longitudinal direction (e.g., a string shape or an elliptical shape), the divided cores 31 a - 31 e are preferably arranged in series in the longitudinal direction. The cross-sectional shape of the hole 32 a may include a part bending in the longitudinal direction or an intersecting part where straight lines cross each other. In this case, in the vicinity of this part, the divided cores 31 a and 31 e among the divided cores 31 a - 31 e are preferably arranged independently from one another. In other words, the core 31 is preferably divided in the vicinity of the bending part or the intersecting part where the straight lines cross each other. According to this structure, the divided cores 31 a - 31 e tend to swing easily, whereby mechanical interface does not tend to occur.

The base parts 31 aa - 31 ea are held between the core holder 32 and the stopping plate 33 , and the divided cores 31 a - 31 e are swingably held by the core holder 32 and the stopping plate 33 .

The sliding part 3 preferably includes a floating structure in which the divided cores 31 a - 31 e float in the core holder 32 . Specifically, as shown in FIG. 4 , the divided core 31 c is preferably positioned on the surface of the stopping plate 33 and at least a part of the divided core 31 c is preferably separated from the core holder 32 . Similar to the divided core 31 c , the divided cores 31 a , 31 b , 31 d , and 31 e are preferably positioned on the surface of the stopping plate 33 and at least some of the divided cores 31 a , 31 b , 31 d , and 31 e are preferably separated from the core holder 32 . The divided cores 31 a - 31 e can move within a predetermined range with respect to the core holder 32 and the stopping plate 33 while they are being held by the core holder 32 and the stopping plate 33 .

The distance D 1 between the inner wall surface of the sliding part holding hole 2 b of the movable die 2 and the plate parts 31 ab - 31 eb is preferably shorter than the distance D 2 between the inner wall surface of the hole 32 a of the core holder 32 and the plate parts 31 ab - 31 eb . Therefore, the plate parts 31 ab - 31 eb of the divided cores 31 a - 31 e can respectively swing in the direction that is perpendicular to the inner wall surface of the hole 2 d (in this example, in the z-axis direction).

The core holder 32 and the stopping plate 33 are each preferably provided with technical means for applying a force to the core holder 32 and the stopping plate 33 from the side of the stopping plate 33 in such a way that the sliding part 3 approaches or is separated from the hole 2 d in the sliding direction of the sliding part 3 . This technical means may be a large variety of mechanisms and devices such as a motor, a hydraulic cylinder, and a cam mechanism. The sliding part 3 is slid in the holes 2 c and 2 d by this technical means. Since the core holder 32 tends to be thicker than the core 31 , the sliding part 3 can stably slide by applying a force to the core holder 32 and the stopping plate 33 from the side of the stopping plate 33 .

(Method of manufacturing Resin Body)

Next, a method of manufacturing the resin body according to the first embodiment will be explained. FIGS. 5-9 are views each showing one process of the method of manufacturing the resin body according to the first embodiment. FIG. 10 is a perspective view showing one example of the resin body according to the first embodiment. FIG. 11 is a schematic view showing operations of the core of the mold of the resin body according to the first embodiment.

As shown in FIGS. 1 and 5 , the resin material is filled into the resin base material molding cavity C 1 from the resin base material molding injection nozzle 4 , thereby forming a resin base material W 1 (resin base material forming process ST 1 ). Specifically, first, while pressing the movable die 2 against the fixed die 1 , the tip of the core 31 of the sliding part 3 is positioned at the distal end of the hole 2 d on the side of the resin base material molding cavity C 1 (in this example, x-axis direction positive side). Accordingly, an opening part 2 da that communicates from the resin base material molding cavity C 1 to the foamed resin part molding cavity C 2 is interrupted. The resin material is injected from the resin base material molding injection nozzle 4 , passes the inflow hole 1 a of the fixed die 1 , and is filled into the resin base material molding cavity C 1 . Since the opening part 2 da is interrupted, the resin material rarely enters the foamed resin part molding cavity C 2 . After the filling process, the resin material is solidified in the resin base material molding cavity C 1 , whereby the resin base material W 1 is formed.

Next, as shown in FIGS. 6 and 7 , the sliding part 3 is separated from the resin base material molding cavity C 1 (sliding part retracting process ST 2 ). In the foamed resin part molding cavity C 2 , the filling space that can be filled with the foamed resin material is increased.

Next, as shown in FIG. 8 , a foamed resin material W 2 a is filled into the foamed resin part molding cavity C 2 from the foamed resin part molding injection nozzle 5 via the inflow hole 2 e (foamed resin filling process ST 3 ).

Lastly, as shown in FIG. 9 , by foaming the foamed resin material W 2 a , a foamed resin part W 2 is formed on the resin base material W 1 (foaming process ST 4 ). The sliding part 3 (see FIG. 9 ) is preferably separated from the resin base material molding cavity C 1 as appropriate.

From the aforementioned processes, a resin body P 10 is formed. As shown in FIG. 10 , one example of the resin body P 10 includes the resin base material W 1 and the foamed resin part W 2 . The resin base material W 1 is a dish-shaped body including a recessed part W 1 a that is concaved in a rectangular parallelepiped shape. The foamed resin part W 2 is arranged in the vicinity of the outer periphery of the resin base material W 1 , and is extended along one side of the recessed part W 1 a and is extended so as to surround both end parts of one side of the recessed part W 1 a.

A large variety of resins may be used for the resin base material W 1 . A resin that can be foamed may be used for the foamed resin part W 2 . This resin that can be foamed includes, for example, thermoplastic elastomer. Specific examples include saturated styrene elastomer, polyolefin, or a compound thereof, or ethylene-propylene rubber, ethylene propylene diene rubber or the like. A foaming agent may be anything that is capable of foam molding elastomer by injection molding, and may be, for example, sodium bicarbonate or azo compounds.

In the aforementioned method of manufacturing the resin body, the mold 10 may be distorted and deformed since heat is given thereto by the resin material, the foamed resin material W 2 a and the like. When, in particular, the aforementioned method of manufacturing the resin body is repeatedly performed, this deformation tends to occur. As shown in FIG. 11 , the movable die 2 is distorted and deformed, and contacts the plate part 31 cb of the divided core 31 c , which is one example of the distal end of the core 31 . However, since the divided core 31 c swings in the direction that is perpendicular to the inner wall surface of the hole 2 d (in this example, the direction along the yz plane, e.g., z-axis direction), the divided core 31 c can swing and move with respect to the hole 2 d before the movable die 2 is deformed. Therefore, mechanical interference between the movable die 2 and the sliding part 3 does not tend to occur. Accordingly, the aforementioned method of manufacturing the resin body can be further repeated. That is, the foamed resin part W 2 and the resin base material W 1 are integrally molded, and the resin body P 10 can be molded using only one mold 10 , without using a plurality of molds. It is therefore possible to reduce the cost of manufacturing the resin body P 10 .

Further, when the core 3 includes a plurality of divided cores (e.g., divided cores 31 a - 31 e ), the divided core tends to swing in the direction that is perpendicular to the inner wall surface of the hole 2 d more easily. Therefore, the divided core can slide with respect to the hole 2 d before the movable die 2 is deformed. Accordingly, the aforementioned method of manufacturing the resin body can be further repeated.

One Modified Example of Core of Mold

Referring next to FIG. 12 , one modified example of the core of the mold of the resin body according to the first embodiment will be explained. FIG. 12 is a schematic view showing the xz cross section of the plate part 31 cb . A core 231 includes a structure the same as those of the divided cores 31 a - 31 e , which are examples of the cores 31 , except that the plate parts 31 ab , 31 bb , 31 cb , 31 db , and 31 eb each include a recessed part 31 f The recessed part 31 f is provided on the distal end surface of the core 231 on the side of the resin base material molding cavity C 1 (in this example, x-axis direction positive side). The shape of the recessed part 31 f is not limited to the shape shown in FIG. 12 , and may be a wide variety of shapes. Further, only one recessed part 31 f may be provided or a plurality of recessed parts 31 f may be provided.

One Modified Example of Method of Manufacturing Resin Body

Referring next to FIGS. 5-9 and 13-17 , one modified example of the method of manufacturing the resin body according to the first embodiment will be explained. One modified example of the method of manufacturing the resin body according to the first embodiment is the same as the aforementioned method of manufacturing the resin body according to the first embodiment except that the core 231 is used. Only the configuration different from that of the aforementioned method of manufacturing the resin body according to the first embodiment will be explained. FIGS. 13-16 are views each showing one process of the method of manufacturing the resin body according to the first embodiment. FIG. 16 is a perspective view showing one example of the resin body according to the first embodiment. While the plate part 31 cb is shown in FIGS. 13-16 , the plate parts 31 ab , 31 bb , 31 db , and 31 eb perform operations similar to those of the plate part 31 cb . It should be noted that in FIGS. 13-16 , the hatching of the movable die 2 is omitted for the sake of clarity. FIG. 17 is a schematic cross-sectional view showing one modified example of the resin body according to the first embodiment.

First, as shown in FIGS. 5 and 13 , in the resin base material forming process ST 1 , the resin material is filled into the resin base material molding cavity C 1 to form the resin base material W 1 . Then, after the resin material is filled into the recessed part 31 f , the resin material is solidified inside the resin base material molding cavity C 1 , thereby forming a resin base material W 11 . The resin base material W 11 includes a plate-shaped part W 11 a and a base material protruding part W 11 b protruded from the plate-shaped part W 11 a . The base material protruding part W 11 b has a shape in which the shape of the recessed part 31 f is transferred.

Next, as shown in FIGS. 6 and 14 , in the sliding part retracting process ST 2 , the sliding part 3 is separated from the resin base material molding cavity C 1 . Then, in the foamed resin part molding cavity C 2 , the filling space that can be filled with the foamed resin material is increased.

Next, as shown in FIGS. 8 and 15 , in the foamed resin filling process ST 3 , a foamed resin material 13 a is filled into the foamed resin part molding cavity C 2 . Then, after the foamed resin material 13 a is made to flow into the recessed part 31 f , the foamed resin material 13 a in the vicinity of the interface with the core 231 is solidified while it is not at least foamed completely, whereby a surface skin part 12 is formed. The surface skin part 12 includes a surface skin body 12 a and a protruding part 12 b protruded from the surface skin body 12 a . The surface skin body 12 a covers the foamed resin material 13 a that has not yet been solidified, and the protruding part 12 b has a shape transferred to the recessed part 31 f . Since the plate part 31 cb of the divided core 31 c includes the recessed part 31 f , the contact area of the surface skin part 12 with the divided core 31 c is large.

Lastly, as shown in FIGS. 9 and 16 , in the foaming process ST 4 , by foaming the foamed resin material 13 a , the foamed resin body 13 is formed. The sliding part 3 is preferably separated from the resin base material molding cavity C 1 as appropriate. The foamed resin body 13 is foamed in such a way that the foaming ratio at least exceeds the foaming ratio of the surface skin part 12 . The surface skin part 12 and the foamed resin body 13 are modified examples of the foamed resin part W 2 (see FIG. 10 ).

From the aforementioned processes, a resin body P 20 shown in FIG. 17 is formed. In the aforementioned modified example of the method of manufacturing the resin body, similar to the aforementioned method of manufacturing the resin body (see FIGS. 5-9 ), the mold may be distorted and deformed since heat is given thereto by the resin material, the foamed resin material or the like. Similar to the aforementioned method of manufacturing the resin body (see FIGS. 5-9 ), the movable die 2 is distorted and deformed, and contacts the core 231 . However, since the core 231 swings, it can slide with respect to the hole 2 d as before. Accordingly, the aforementioned method of manufacturing the resin body can be further repeated.

Further, the plate part 31 cb includes the recessed part 31 f . Therefore, in the foaming process ST 4 , when the foamed resin material 13 a is filled into the foamed resin part molding cavity C 2 , the contact area of the surface skin part 12 with the plate part 31 cb is large. The surface skin part 12 is a part of one modified example of the foamed resin part W 2 and the plate part 31 cb of the divided core 31 c is a part of one modified example of the core 31 of the sliding part 3 . That is, it is possible to increase the contact area of the foamed resin part with the sliding part. Since it is possible to prevent the foamed resin part from being away from the sliding part, it is therefore possible to mold the foamed resin part with a high precision.

One Modified Example of Resin Body

Next, with reference to FIG. 17 , the resin body P 20 , which is one modified example of the resin body P 10 , will be explained.

As shown in FIG. 17 , the resin body P 20 includes the resin base material W 11 , the surface skin part 12 , and the foamed resin body 13 .

The resin base material W 11 includes a plate-shaped part W 11 a and a base material protruding part W 11 b . The base material protruding part W 11 b is provided between the resin base material W 11 and the foamed resin body 13 and is protruded from the plate-shaped part W 11 a to the foamed resin body 13 . The resin base material W 11 may have a shape the same as that of the resin base material W 1 shown in FIG. 10 .

The foamed resin body 13 is arranged on the surface of the resin base material W 11 . The surface skin part 12 includes a surface skin body 12 a and a protruding part 12 b . The surface skin body 12 a covers the surface of the foamed resin body 13 . The protruding part 12 b is protruded from the surface skin body 12 a on a side opposite to the resin base material W 11 (in this example, on the x-axis negative side). The surface skin part 12 and the foamed resin body 13 may each have a shape that is the same as that of the foamed resin part W 2 shown in FIG. 10 .

The foaming ratio of the foamed resin body 13 is higher than the foaming ratio of the surface skin part 12 . The foamed resin body 13 is less rigid than the surface skin part 12 and has a high cushioning performance. On the other hand, the surface skin part 12 is more rigid than the foamed resin body 13 and has a high sealing performance.

Note that the present disclosure is not limited to the aforementioned embodiment and may be changed as appropriate without departing from the spirit of the present disclosure.

From the disclosure thus described, it will be obvious that the embodiments of the disclosure may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure, and all such modifications as would be obvious to one skilled in the art are intended for inclusion within the scope of the following claims.