JP5779916B2 - Injection mold equipment - Google Patents

Description

  The present invention relates to an injection mold apparatus, and more particularly to an injection mold apparatus in which a hot runner and a cold runner provided in series with the hot runner are used in combination to extend the hot runner. .

  When injection molding long and large resin molded products as represented by automobile bumper fascia, the gates are opened and closed sequentially using a multi-point gate with valves (multiple valve gates) and melted. There is a molding method in which resin material is injected and filled. Such a molding method is premised on the adoption of a hot runner system, and is generally called a cascade injection molding method or the like.

  On the other hand, in such an injection molding method using a hot runner system and a valve gate, a cold runner provided in series with the hot runner is provided separately from the hot runner opened and closed by the valve gate. For example, Japanese Patent Application Laid-Open No. 2004-209904 proposes a mold apparatus that is used in combination.

  In general injection molds, a heat insulating layer is formed on a cavity wall surface or the like which is a product shape space for the purpose of improving moldability. JP-A-8-25428 and JP-A-8-66927 In addition to the publication, it is proposed in Patent Documents 1 and 2.

JP 2000-108156 A International Publication No. 2007/015390

  However, as the length of the cold runner used in combination with the hot runner becomes longer, it becomes more difficult to stably maintain the fluidity of the molten resin material supplied from the hot runner side on the cold runner side. Leaving room for. In particular, in the techniques described in Patent Documents 1 and 2, not only the use of a hot runner and a cold runner is used, but also consideration is given to ensuring the fluidity of the molten resin material when the length of the cold runner is increased. Not.

  The present invention has been made paying attention to such problems, ensuring the fluidity of the molten resin material in a cold runner used in combination with a hot runner, preventing solidification of the resin material, and maintaining it. An excellent mold apparatus for injection molding is provided.

  The present invention provides a hot runner to which a molten resin material is supplied and a cold runner having one end connected to the hot runner and the other end connected to a cavity via a gate. It is presupposed that it is an injection mold apparatus in which the cold runner is formed on a split surface between a pair of mold elements that are opened when a molded product is taken out.

In addition, the cold runner is formed from a groove formed on the dividing surface of one mold element and a dividing surface of the other mold element, and a heat insulating layer is formed in the groove, and grooves are divided with the heat insulating layer as divided block portions closer to the hot runner of the hand mold element is formed. For example, a ceramic sheet or the like is used as the heat insulating layer.

  Therefore, in this invention, even if the length of the cold runner in series relation with the hot runner becomes long, it becomes possible to ensure the fluidity of the molten resin material in the cold runner. Furthermore, in the portion of the cold runner that is close to the hot runner, the heat insulation layer is expected to deteriorate or break by repeatedly receiving the inflow injection pressure from the hot runner side, but that portion is divided as a divided block. Thus, even if the heat insulating layer is deteriorated or broken, it can be easily replaced.

  According to the present invention, by ensuring the fluidity of the molten resin material in the cold runner, it is possible to prevent the resin material from solidifying, and it is possible to optimally control the injection speed and injection pressure required for molding. In particular, even when a long and large resin molded product such as an automobile bumper fascia is formed, it can be formed without difficulty.

  Moreover, even if the heat insulation layer deteriorates or breaks by repeatedly receiving the inflow injection pressure from the hot runner side in the portion close to the hot runner in the cold runner, that portion is divided as a divided block, It is possible to easily replace only the portion, and the maintenance is excellent.

The figure which shows the 1st form for implementing the injection molding die apparatus which concerns on this invention, and is a perspective view which shows schematic structure of the bumper fascia of a motor vehicle as an example of the molded article by injection molding. Sectional explanatory drawing which shows the structure of the Q section equivalent part of FIG. 1 among the metal mold | die apparatuses for injection-molding the bumper fascia of FIG. Explanatory sectional explanatory drawing which shows the detail of the cold runner of FIG. The C direction arrow directional view in the mold opening state of FIG. Explanatory sectional explanatory drawing in alignment with the AA of FIG. The enlarged view of the R section equivalent part of FIG. Cross-sectional explanatory drawing which shows the modification of the stepped structure shown in FIG.

  1 to 4 show a more specific form for carrying out the injection molding die apparatus according to the present invention. In particular, FIG. 1 shows a bumper fascia Bf of an automobile as an example of a molded product by injection molding. 1 shows the structure of the portion corresponding to the Q portion of FIG. 1 in the mold apparatus for injection molding the bumper fascia Bf.

  As shown in FIG. 1, the bumper fascia Bf belongs to a long and large part among resin parts for automobiles, and the so-called length (the length in the front-rear direction of the bumper fascia Bf) is large. As mentioned above, it is molded by a cascade injection molding method using a hot runner block and a plurality of valve gates.

  In this case, most of the bumper fascia Bf is formed by a so-called runnerless system by sequentially opening and closing a plurality of valve gates, but a part of the bumper fascia Bf, for example, the bumper fascia Bf shown in FIG. As for the bumper side portion Sb, a cold runner is used in combination because of restrictions on the layout of the hot runner block.

  FIG. 1 shows that the cold runner trace Rs and the gate trace Gs which are traces of the cold runner 4 are taken out from the mold apparatus while attached to the upper part of the bumper side part Sb of the bumper fascia Bf which is a molded product as a non-product part region In the subsequent state, the cold runner trace Rs and the gate trace Gs are cut and removed from the bumper fascia Bf which is a molded product in a subsequent process.

  In FIG. 2, 1 is a core block as one mold element, 2 is a cavity block as the other mold element, and 3 is formed with the core block 1 and the cavity block 2 being clamped. The cavity as a product shape part space to be performed is shown. Further, a cold runner 4 corresponding to the cold runner trace Rs in FIG. 1 is provided so as to be offset in a direction orthogonal to the paper surface of FIG.

  Here, as apparent from FIG. 1, the bumper side portion Sb and the cold runner trace Rs incident on the bumper side portion Sb partially overlap in the left-right direction. Of these, regarding the relationship between the portion corresponding to the bumper side portion Sb and the cold runner 4, in fact, the bumper fascia Bf partially overlaps in the left-right direction (vertical direction in FIG. 2). Become. However, in FIG. 2, the cold runner 4 is drawn outside the position corresponding to the bumper side portion Sb of the cavity 3 in order to avoid complication due to the overlapping of both in the drawing.

  A hot runner block 5 is attached to the cavity block 2 side, and a molten resin material is supplied to the hot runner block 5 from an injection nozzle 7 through a sprue bush 6. A plurality of runner sleeves 8 that substantially function as hot runners face the cavity 3 from the hot runner block 5 side (however, only one is shown in FIG. 2). The valve pin 9 that is driven back and forth by is inserted. By actively opening and closing the gate 11 on the tip end side of the runner sleeve 8 by the valve pin 9, it is possible to inject and block the molten resin material to the cavity 3, thereby exhibiting the function as a valve gate. Will be.

  The hot runner block 5 is provided with another runner sleeve 12 that functions as a hot runner, and a valve pin 13 that is driven forward and backward by a cylinder 14 is inserted in the runner sleeve 12. Is facing the secondary sprue portion 15 of the cold runner 4. Then, the valve pin 13 actively opens and closes the secondary sprue portion 15 on the tip end side of the runner sleeve 12 as a gate, thereby enabling injection and blocking of the molten resin material to the cold runner 4. The function as a gate is demonstrated. That is, the cold runner 4 is provided in series with the runner sleeve 12 in the form of extending the hot runner formed by the hot runner block 5 and the runner sleeve 12, and a valve gate is provided at the secondary sprue portion 15 which is a connection portion between them. The function of will be demonstrated.

  The hot runner block 5 and each of the runner sleeves 8 and 12 are heated to a predetermined temperature by a heater (not shown) as is well known, and the fluidity of the molten resin material therein is maintained.

  3 shows details of the cold runner 4 shown in FIG. 2, and FIG. 4 shows a view in the direction of the arrow C in the mold open state of FIG. Further, FIG. 5 shows an enlarged cross-sectional view along the line AA of FIG. The cold runner 4 is formed between the divided blocks 16, 17 functioning as a part of the core block 1 of FIG. 2 which is one mold element, and the cavity block 2 of FIG. 17 and the cavity block 2 are opened and closed, that is, the mold is opened each time the bumper fascia Bf as a molded product is taken out.

  Note that a part of the core block 1 forming the cold runner 4 has a split structure by the divided blocks 16 and 17 and a detachable structure because the portion of the heat insulating layer 23 described later is damaged or deteriorated. This is to facilitate exchange. Of the divided blocks 16 and 17, at least the divided block 16 on the side close to the runner sleeve 12 that functions as a hot runner is preferably formed of a low thermal conductive material.

  More specifically, a groove portion 19 having a substantially semicircular cross section as shown in FIG. 5 is formed on the dividing surface 18 of the divided blocks 16 and 17 with the cavity block 2 as shown in FIG. A so-called semicircular (half-round) cold runner 4 is formed by the surface 20 closing the groove 19. A side gate 21 connected to the cavity 3 functioning as a product shape portion space is formed at one end portion (terminal portion) of the cold runner 4 in the longitudinal direction, and a terminal portion on the side gate 21 side stores cold slugs and the like. Slag well 22. Further, the other end portion (starting end portion) in the longitudinal direction of the cold runner 4 functions as the secondary sprue portion 15 as described above, and the secondary sprue portion 15 is based on FIG. As described above, the runner sleeve 12 that functions as a valve gate is faced.

  Here, even if the cold runner 4 is formed in series with the runner sleeve 12 extending in the form of the runner sleeve 12 functioning as a hot runner, the cold runner 4 is used in combination with the hot runner when the length is increased. There is a possibility that the effect of the above will be halved and solidification of the molten resin material in the cold runner 4 will be promoted more than necessary. As a countermeasure, in this embodiment, a heat insulating layer 23 is provided in the flow path as the cold runner 4 so that the cooling and solidification in the process in which the molten resin material flows through the cold runner 4 is considered to be slow. .

  More specifically, as shown in FIGS. 3, 4, and 5, the portion of the divided surface 18 on both divided blocks 16, 17 side that faces the cold runner 4 space and forms the cold runner 4, that is, A portion corresponding to the bottom portion of the groove portion 19 having a substantially semicircular cross section formed on both divided blocks 16 and 17 side as the cold runner 4 and excluding the portion functioning as the slag well 22, along the longitudinal direction. For example, a heat insulating layer 23 having a predetermined thickness is formed by attaching a ceramic sheet. The thickness of the heat insulating layer 23 gradually changes from the deepest part of the groove part 19 toward the open side of the groove part 19 or the general part of the dividing surface 18, that is, gradually toward the dividing surface 20 on the cavity block 2 side. Therefore, it disappears immediately before reaching the general part of the dividing surface 18 in which the groove part 19 is formed (the part of the dividing surface 18 other than the groove part 19). That is, the cross-sectional shape of the heat insulating layer 23 provided in the groove portion 19 is substantially a crescent shape as is apparent from FIG.

  Thereby, in the depth direction of the groove part 19 which functions as the cold runner 4, it has become the form which gave the thermal gradient to the heat insulation effect by the heat insulation layer 23. FIG. At the same time, the heat insulating layer 23 is not provided on the portion of the groove portion 19 that is close to the general portion of the dividing surface 18, the dividing surface 18 itself, and the other dividing surface 20, and a so-called non-insulating structure is obtained. ing.

  Here, FIG. 6 shows an enlarged detail of the R portion of FIG. As is clear from FIGS. 3 and 6, both the divided blocks 16 and 17 that function as a part of the core block 1 are divided from the core block 1, so that a butt portion between both the divided blocks 16 and 17. 24 is inevitable, and a part of the butting portion 24 faces the space of the cold runner 4. At the same time, the heat insulating layer 23 is also divided in the longitudinal direction of the cold runner 4 at a position corresponding to the butted portion 24 between the two divided blocks 16 and 17. Here, the heat insulating layer attached to the divided block 16 side is referred to as 23a, and the heat insulating layer attached to the divided block 17 side is referred to as 23b.

  Therefore, the end portions 25a and 25b of the heat insulating layers 23a and 23b located on both sides of the abutting portion 24 are gradually changed so that the thickness gradually decreases toward the abutting portion 24 side. In particular, it is formed in a tapered shape inclined toward the abutting portion 24 with a downward slope. In addition, the tapered end portions 25a and 25b disappear immediately before reaching the abutting portion 24, and in a slight region C on both sides of the abutting portion 24, the heat insulating layer 23 does not exist and the non-insulating structure is formed. It has become. That is, in the region C, the material of both the divided blocks 16 and 17 itself is directly exposed. Instead of the tapered terminal portions 25a and 25b shown in FIG. 6, it may have a shape inclined with an arc surface.

  Therefore, according to the injection mold apparatus configured as described above, when the bumper fascia Bf as shown in FIG. 1 is formed, most of the bumper fascia Bf is configured by opening and closing a plurality of valve gates sequentially. On the other hand, in the bumper fascia Bf, the vicinity of the upper part of the bumper side portion Sb is formed by using the cold runner 4 in series with the hot runner corresponding to the runner sleeve 12 in combination with the runnerless method. This is as described above.

  When the runner sleeve 12 that functions as a valve gate is opened by the valve pin 13, the molten resin material is injected from the runner sleeve 12 side to the cold runner 4 side through the secondary sprue portion 15. 4 is injected to the cavity 3 side via the side gate 21 to form a part of the bumper side portion Sb of the bumper fascia Bf.

  In this case, since the heat insulating layer 23 is provided along the longitudinal direction of the cold runner 4, the cooling and solidifying action in the process in which the molten resin material flows through the cold runner 4 becomes slow. Even if the length of the resin is increased, the solidification of the molten resin material is prevented and the injection speed and injection pressure required for forming the bumper fascia Bf can be controlled.

  Further, by providing a thermal gradient according to the thickness change of the heat insulating layer 23 in the depth direction of the cold runner 4 (depth direction of the groove portion 19), the heat insulation effect is greater in the portion closer to the deepest portion of the groove portion 19. While the cooling effect by the divided blocks 16 and 17 is slow, the portion closer to the divided surface 20 on the cavity block 2 side in the cold runner 4 has a poor heat insulation effect and is more likely to receive a cooling promotion effect by the cavity block 2 itself. . As is apparent from FIG. 5, the heat insulating layer 23 is formed at a portion where the general portion of the dividing surface 18 on the divided blocks 16, 17 side and the dividing surface 20 on the cavity block 2 side are abutted (so-called parting line equivalent portion). Has disappeared and a so-called non-insulating structure in which the material of the divided blocks 16 and 17 or the cavity block 2 itself is exposed is formed. For this reason, a portion of the so-called parting line equivalent portion or groove portion 19 that is very close to the parting line equivalent portion does not exhibit a heat insulating effect, and the molten resin material is cooled by the divided blocks 16 and 17 or the cavity block 2 itself. Solidification is promoted. As a result, it is possible to prevent the occurrence of burrs at the part corresponding to the so-called parting line.

  In addition, if the heat insulation effect by the heat insulation layer 23 becomes too large, the cooling promotion effect becomes relatively slow, and a takeout failure due to insufficient cooling and solidification may occur at the time of taking out the molded product. The coexistence and adjustment of the effect and the cooling promotion effect due to the exposure of the divided blocks 16 and 17 are performed by adjusting the thickness dimension of the heat insulating layer 23.

  Here, as is apparent from FIG. 3, in the secondary sprue portion 15 facing the runner sleeve 12 that functions as the hot runner of the cold runner 4, the inflow injection pressure from the runner sleeve 12 side is changed in the direction perpendicular to the plane. Therefore, it is expected that the heat-insulating layer 23a of the part is deteriorated or broken earlier than other parts. As a countermeasure, a portion of the cold runner 4 that is close to the runner sleeve 12 and that includes the secondary sprue portion 15 has a divided structure as a divided block 16, so that the secondary sprue portion 15 is formed as described above. When the corresponding heat insulating layer 23a is deteriorated or damaged, the divided block 16 is detached and the heat insulating layer 23a attached to the divided block 16 is replaced with the divided block 16 together.

  Further, in the abutting portion 24 between the divided blocks 16 and 17, when the end portions 25a and 25b of both the heat insulating layers 23a and 23b are simply abutted without being tapered as shown in FIG. Due to the heat insulating effect of the heat insulating layers 23a and 23b, the molten resin material becomes difficult to solidify, and the molten resin material enters the gaps between the butted portions 24 of the divided blocks 16 and 17 to generate burrs due to resin leakage and the mold It cannot be denied that there is a risk of damage.

  In this regard, in this embodiment, as shown in FIG. 6, in the region C corresponding to both sides of the abutting portion 24 between the divided blocks 16 and 17, the heat insulating layers 23 a and 23 b are interrupted, and both the divided blocks 16 and 17 are separated. The material is directly exposed to the space of the cold runner 4. Therefore, in the portion corresponding to the region C, by promoting the solidification of the molten resin material by the material of the divided blocks 16 and 17, it is possible to prevent the molten resin material from entering the gap of the butt portion 24. It is possible to prevent the cold runner trace Rs shown in FIG. 1 from sticking to the divided blocks 16 and 17 when opened.

  Further, since the end portions 25a and 25b of the heat insulating layers 23a and 23b in both the divided blocks 16 and 17 are tapered, the divided blocks 16 and 17 are exchanged when the divided block 16 is replaced. Even if it interferes, it becomes possible to prevent the heat insulation layers 23a and 23b from being damaged.

  Here, as shown in FIG. 1, the bumper side portion of the bumper fascia Bf which is a molded product (product) as the cold runner trace Rs and the gate trace Gs where the traces of the cold runner 4 and the side gate 21 are non-product portion regions. As described above, it is taken out of the mold apparatus while attached to the upper part of Sb. When removing the bumper fascia Bf, if the core block 1 and the cavity block 2 shown in FIG. 2 are separated from each other in the left-right direction in FIG. 2 and the mold is opened, the bumper fascia Bf is left on the core block 1 side. become.

  Therefore, in order to avoid undercut of the flange portion F in the end portion of the bumper side portion Sb in FIG. 1, the end portions of the left and right bumper side portions Sb are used by using the degree of freedom of the slide core (not shown) on the core block 1 side. Slightly elastically deform in directions away from each other. By doing so, the undercut of the flange portion F at the end portion of the bumper side portion Sb is avoided, the bumper side portion Sb is peeled off from the core block 1, and the cold runner trace Rs attached to the bumper side portion Sb. Further, the gate trace Gs is also detached from the divided blocks 16 and 17 in FIG. Thereafter, the bumper fascia Bf is protruded in the direction b in FIG.

  Furthermore, as shown in FIG. 7, if necessary, in a position facing the groove 19 on the divided blocks 16 and 17 side of the dividing surface 20 on the cavity block 2 side, separately from the heat insulating layer 23 provided on the groove 19. It is also possible to provide a heat insulating layer 33 having a predetermined thickness. In this case, the heat insulation effect by the heat insulation layers 23 and 33 can be expected both on the divided blocks 16 and 17 forming the cold runner 4 and on the cavity block 2 side. In particular, the length of the cold runner 4 is further increased. It is convenient in case.

1 ... Core block (mold element)
2. Cavity block (mold element)
3 ... Cavity 4 ... Cold runner 5 ... Hot runner block 8 ... Runner sleeve (hot runner)
9 ... Valve pin 12 ... Runner sleeve (hot runner)
13 ... Valve pin 16 ... Division block (mold element)
17 ... Divided block (mold element)
DESCRIPTION OF SYMBOLS 18 ... Dividing surface 19 ... Groove part 20 ... Dividing surface 21 ... Side gate 23 ... Heat insulation layer 23a ... Heat insulation layer 23b ... Heat insulation layer 24 ... Butting part 25a ... Terminal part 25b ... Terminal part 33 ... Thermal insulation layer Bf ... Bumper fascia (molded article) )
Rs ... Cold Runner Trace

Claims (5)

A hot runner to which a molten resin material is supplied;
A cold runner having one end connected to the hot runner and the other end connected to the cavity via a gate;
With
An injection mold apparatus in which the cold runner is formed on a split surface between a pair of mold elements that are opened when a molded product is removed,
The cold runner is formed from a groove formed on the dividing surface of one mold element and a dividing surface of the other mold element,
A heat insulating layer is formed in the groove ,
Injection mold apparatus, wherein a portion close to the hot runner are divided with the heat insulating layer as divided block out of the mold components of one-way that the groove is formed. 2. The mold apparatus for injection molding according to claim 1, wherein the heat insulating layer has a crescent-shaped cross section . The injection according to claim 2, wherein a start portion of the groove portion that is formed in the divided block and functions as a cold runner includes a portion that receives the inflow injection pressure from the hot runner from the plane crossing direction. Mold equipment for molding. The butted part of the one mold element and the divided block faces the cold runner space,
4. The mold apparatus for injection molding according to claim 3, wherein the abutting portion has a non-insulating structure without providing a heat insulating layer . The hot runner is formed with a hot runner block,
5. The mold apparatus for injection molding according to claim 3 , wherein the connecting portion between the hot runner and the cold runner is opened and closed by a valve gate .

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