JP2013240999A - Injection molding equipment and reinforcement rib extrusion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide injection molding equipment enabling the improvement of mold release properties of a thin-walled resin component for a vehicle while preventing the sinking of a design face by using a simple structure and method, and a reinforcement rib extrusion device using the injection molding equipment.SOLUTION: Injection molding equipment 100 for a vehicle resin component 10 (10A) in which a plurality of reinforcement ribs 2 (2A) are installed on a back face side 12 of a panel body 1 in a projecting manner includes a cavity mold 41, a core mold 31 and a reinforcement rib cavity mold 51 (51A). The reinforcement rib cavity mold 51 (51A) is nested into the core mold 31. The reinforcement rib cavity mold 51 (51A) includes a cooling circuit 52 (52A) controlled independently of cooling circuits 44, 34 of the cavity mold 41 and the core mold 31.

Description

  The present invention relates to an injection molding apparatus for injection molding of resin parts for vehicles used for interior and exterior parts of automobiles and a reinforcing rib extrusion apparatus used for the injection molding apparatus.

Generally, interior and exterior parts of automobiles (for example, bumpers and quarter trims) are provided with a panel body having a design surface that emphasizes the appearance of the design, and reinforcing ribs for ensuring the rigidity of the panel body. Yes. In addition, automobile interior / exterior parts are often resin parts for vehicles manufactured by an injection molding apparatus in order to integrally mold a panel body and reinforcing ribs and increase the degree of freedom of the design surface.
In order to cope with recent global environmental problems, the resin parts for vehicles are required to be further thinned and highly rigid. However, as the resin parts for vehicles are made thinner, sinks tend to occur on the surface of the panel body corresponding to the base end of the reinforcing rib, and when the reinforcing rib is solidified, it shrinks and adheres to the mold groove. There was a problem that it was difficult to release.
For this reason, a technique relating to an injection molding apparatus that enhances the mold release property while ensuring the appearance of the design of the resin component for a vehicle has been developed (see, for example, Patent Documents 1-3).

For example, in the technique of Patent Document 1, in an injection mold for molding a resin molded product in which a reinforcing rib is formed on a thin plate portion, at least the reinforcing rib forming surface of the molding surface on the reinforcing rib forming side is used. A fine unevenness is formed on the portion including the concave portion and the periphery thereof so as to make point contact with the molten resin, and the glass of the resin is used for both the mold on the reinforcing rib forming side and the mold facing the reinforcing rib. A temperature control mechanism for controlling to a predetermined temperature lower than the transition point or the crystallization temperature is provided.
Heating both molds slows down the solidification of the thicker reinforcing ribs compared to the thin plate portion, and the molten resin in the reinforcing ribs is pulled in the thin plate portion direction, while the surface of the thin plate portion is heated. Therefore, it is possible to realize a state in which wettability is high, that is, a close contact state and a state in which sink marks are hardly generated on the design surface side of the thin plate portion. In addition to this, the mold release of the molten resin can be promoted by forming minute recesses and protrusions that are in point contact with the molten resin in the recesses for forming the reinforcing ribs and the periphery thereof.

Moreover, the technique of patent document 2 is for the thermoplastic resin injection molding which has a cavity type | mold, a core type | mold, and the cavity part formed between this cavity type | mold and this core type | mold and filled with molten resin. The mold is characterized in that the cavity mold has a heat insulating layer on the surface thereof, and the core mold has a releasable heat insulating layer having a releasing property and a heat insulating function on the surface portion.
According to this mold for molding a thermoplastic resin, when the molten resin is filled in the cavity portion, the temperature of the cavity mold is instantaneously increased, wettability is developed, and the molten resin adheres strongly to the mold surface. On the other hand, since the core mold surface has a releasable heat insulating layer, the core mold surface is kept in contact with the molten resin but not in close contact. For this reason, the molten resin on the core side is immediately released from the core mold surface, and an air heat insulating layer is formed between the molten resin on the core surface and the cooling rate is slowed down. As a result, only the resin on the core side contracts while the resin on the cavity mold surface is in close contact, and solidification of the molded product can be completed without causing sink marks on the molded product surface on the cavity side. it can.

  The technique of Patent Document 3 is a method in which a molded product injection-molded by a fixed mold and a movable mold is released by an extrusion pin provided on the movable mold, and the molded product is fixed by the extrusion pin before the mold is opened. The release force when releasing the molded product from the movable mold matches the release force when releasing the molded product from the fixed mold while maintaining pressure contact toward the cavity surface. Open the mold until just before. After that, the mold opening is completed with the molded product attached to the movable mold, and the molded product is released from the movable mold with an extrusion pin, thereby reducing the mold release force of the molded product in the resin mold. is there.

JP-A-2005-313330 JP-A-6-218769 Japanese Patent Laid-Open No. 7-323445

However, Patent Documents 1-3 have the following problems.
That is, in the technique of Patent Document 1, after injecting a molten resin, both the fixed mold and the movable mold are heated, and the molten resin is solidified while maintaining a constant temperature. Productivity in injection molding is significantly reduced. In particular, if the thickness of the reinforcing rib is made thinner than the thickness of the thin plate (corresponding to the panel main body), the reinforcing rib must be heated to a higher temperature in order to prevent the solidification of the reinforcing rib. This leads to a further increase in the productivity, and the problem that productivity in the injection molding is lowered becomes remarkable. In addition, in the technique of Patent Document 1, fine irregularities that are in point contact with the molten resin are formed on and around the portion including the concave portion for forming the reinforcing rib (for example, formed by electroless nickel plating) This is not preferable because the mold manufacturing cost increases.

  Next, in the technique of Patent Document 2, the cavity mold has a heat insulating layer on the surface portion, and the core mold has a releasable heat insulating layer having a releasability and heat insulating function on the surface portion. As in the first technique, the solidification time increases, and the productivity in injection molding decreases. Further, the heat insulating layer (for example, a plate made of ceramics) may be cracked or peeled off. Therefore, in the technique of Patent Document 2, a decrease in durability in the injection mold as well as a decrease in productivity in the injection molding becomes a problem.

In this regard, the technique disclosed in Patent Document 3 does not cause a problem that productivity in injection molding is reduced due to an increase in solidification time.
However, in the technique of Patent Document 3, a measurement detection mechanism for measuring a movable mold opening stroke is provided in the vicinity of the movable mold. The measurement detection mechanism measures the movable mold opening stroke, and this measurement. The operation of the clamping cylinder unit is controlled based on the value. In addition, another measurement detection mechanism for measuring the movement stroke of the push pin is provided in the vicinity of the push rod, and the operation of the push cylinder unit is controlled based on the measurement value measured by the measurement detection mechanism. ing. In this way, a plurality of measurement detection mechanisms and control devices are required, leading to an increase in complexity and cost of the injection molding apparatus.
In the technique of Patent Document 3, a molded product attached to a movable mold by molding shrinkage is pressed with an extrusion pin. Therefore, if the thickness of the molded product (corresponding to the panel body) is reduced, deformation or whitening due to pressing force is caused. The fear increases.

  The present invention has been made to solve the above-described problems, and is an injection molding that improves the releasability of a thin resin component for a vehicle while preventing the design surface from sinking with a simple structure and method. It is an object of the present invention to provide a reinforcing rib extrusion device used for the device and its injection molding device.

In order to solve the above problems, an injection molding apparatus and a reinforcing rib extrusion apparatus according to the present invention have the following configuration.
(1) An injection molding device for a resin component for a vehicle in which a plurality of reinforcing ribs project from the back side of the panel body,
A cavity mold, a core mold, and a reinforcing rib cabinet mold, wherein the reinforcing rib cabinet mold is nested in the core mold;
The reinforcing rib cabinet type has a cooling circuit controlled independently of the cabinet type and core type cooling circuits.

(2) In the injection molding apparatus described in (1),
The mold cooling temperature of the reinforcing rib cabinet mold is higher than the mold cooling temperature of the cabinet mold and the core mold.
(3) In the injection molding apparatus described in (1) or (2),
The mold type for reinforcing ribs is formed by grooving a zinc alloy casting having a higher thermal conductivity than the mold type and the core type.
(4) In the injection molding apparatus described in any one of (1) to (3),
An elevating device for elevating and lowering the panel body, and a reinforcing rib pushing device for extruding the reinforcing rib,
The pushing stroke length of the reinforcing rib pushing device is set to be equal to or less than the lifting stroke length of the lifting device.
(5) In the injection molding apparatus described in any one of (1) to (4),
A cylindrical body is formed at the intersection of the reinforcing ribs, and a cylindrical body extrusion device for extruding the cylindrical body is provided.

(6) A reinforcing rib extrusion device used for the injection molding device described in (4),
A rib extruding pin that contacts the general portion of the reinforcing rib;
An extruding plate that holds the rib extruding pin up and down; and
A telescopic member that expands and contracts between the lifting plate of the lifting device and the extrusion plate;
After the push-out plate reaches the upper end as the elevating plate rises, the telescopic member is shortened by further raising of the elevating plate.
(7) In the reinforcing rib extrusion device described in (6),
The gas in the cavity for reinforcing ribs escapes from the sliding portion of the rib pushing pin.

Next, operations and effects of the injection molding apparatus and the reinforcing rib extrusion apparatus according to the present invention will be described.
(1) An injection molding device for resin parts for vehicles in which a plurality of reinforcing ribs project from the back side of the panel body, comprising a mold, a core, and a mold for reinforcing rib, and a mold for reinforcing rib Is characterized by having a cooling circuit controlled independently from the cooling circuit of the cavity type and the core type. Thus, it is possible to improve the releasability of the thin resin component for a vehicle while preventing the design surface from sinking.

In other words, the mold type includes a mold type, a core type, and a mold type for reinforcing ribs, and the mold type for reinforcing ribs is nested in the core type. And can be provided separately and independently. Further, since the reinforcing rib mold is nested in the core mold, it is easy to block the transmission of mold temperature between the reinforcing rib mold and the core mold. In addition, since the reinforcing rib cavity type cooling circuit is controlled independently of the cavity type and core type cooling circuits, even if the panel body and the entire reinforcing rib thickness are reduced, The cooling temperature optimum for the thickness of the reinforcing rib can be achieved, and the solidification time of the panel main body and the reinforcing rib can be shortened without causing sinking or the like of the panel main body.
Therefore, according to the injection molding apparatus of (1), it is possible to improve the releasability of the thinned resin part for a vehicle while preventing the design surface from sinking with a simple structure and method.

(2) In the injection molding apparatus described in (1), the mold cooling temperature of the reinforcing rib mold is higher than the mold cooling temperature of the mold and the core mold. By controlling the mold cooling temperature so as to suppress the molding shrinkage of the reinforcing ribs, the releasability of the reinforcing ribs can be further improved. That is, by making the temperature on the reinforcing rib side higher than the temperature on the panel body side at the time of mold release, the molding shrinkage amount of the reinforcing rib can be relatively reduced compared to the molding shrinkage amount of the panel body. By providing a difference in the amount of molding shrinkage between the reinforcing rib and the panel body, it is possible to reduce mold biting of the reinforcing rib and improve mold release properties. In addition, it is preferable that the cooling temperature of the mold type for the reinforcing rib is about 50 ° C., and the cooling temperature of the mold type and the core type is about 20 ° C.

(3) In the injection molding apparatus described in (1) or (2), the reinforcing rib cavity mold is formed by grooving a zinc alloy casting having a higher thermal conductivity than the cavity mold and the core mold. As a result, the mold temperature of the mold type for the reinforcing ribs becomes substantially uniform as a whole without being affected by the mold temperature of the mold type and the core type, and the vehicle is thinned while preventing the design surface from sinking. The mold releasability of the resin part can be further improved.
Moreover, since the mold type for reinforcing ribs is a zinc alloy casting, the machinability is greatly improved compared to the high-strength alloy steel generally used for the mold type and the core type. For example, groove processing for reinforcing ribs having a width of about 0.5 mm and a depth of about 5.0 to 6.0 mm can be performed using an end mill. Therefore, it is possible to easily manufacture a reinforcing rib cavity mold that realizes an ultra-thin reinforcing rib.

(4) The injection molding apparatus according to any one of (1) to (3), comprising a lifting device for lifting and lowering the panel body and a reinforcing rib pushing device for pushing the reinforcing rib, and a reinforcing rib pushing device. Since the pushing stroke length of the reinforcing rib is set to be equal to or less than the lifting stroke length of the lifting device, the reinforcing rib pushing device is sufficient for the stroke length to push the reinforcing rib out of the mold groove for the reinforcing rib. The longer stroke length can be assigned to the removal stroke length after molding so that the lifting device that lifts and lowers the panel body plays the role. Therefore, even if the diameter of the rib extruding pin that extrudes the thinned reinforcing rib is small, the stroke length is short, so that problems such as breakage of the rib extruding pin in the reinforcing rib extruding device hardly occur.
In addition, since the reinforcing rib extruding device is released by directly extruding the reinforcing rib, it is possible to effectively release the mold biting of the reinforcing rib, and there are problems such as deformation and whitening of the panel body. Less likely to occur.

(5) In the injection molding apparatus described in any one of (1) to (4), a cylindrical body is formed at a crossing portion of the reinforcing ribs, and the cylindrical body is extruded. Since the extrusion load is distributed to the reinforcing ribs adjacent to the intersecting portion, the extrusion load acting on the panel main body and the reinforcing ribs can be reduced. As a result, even if the entire panel main body and the reinforcing ribs are made thinner, the risk of problems such as deformation and whitening of the panel main body and the reinforcing ribs during mold release can be further reduced.

(6) A reinforcing rib extrusion device used in the injection molding apparatus described in (4), wherein a rib extrusion pin that abuts on a general portion of the reinforcement rib, an extrusion plate that holds the rib extrusion pin up and down, and an elevation A telescopic member that expands and contracts between the lifting plate and the extrusion plate of the apparatus, and the elastic member is shortened by further rising of the lifting plate after the extrusion plate reaches the upper end as the lifting plate rises Therefore, with a simple structure and method, it is possible to improve the releasability of the thinned resin component for a vehicle while preventing the design surface from sinking.

In other words, the extruding plate that holds the rib extruding pin so that it can be raised and lowered is such that after the extruding plate reaches the upper end as the elevating plate rises, the stretchable member is shortened by further raising of the elevating plate. The stroke length of the rib extruding pin can be shortened by shortening the stretchable member while improving the releasability by extruding the reinforcing rib. Since the stroke length of the rib extruding pin is shortened, problems such as breakage, bending and galling of the rib extruding pin can be reduced.
Moreover, since it is only necessary to provide an elastic member between the lifting plate and the extrusion plate of the lifting device, a plurality of measurement detection mechanisms and control devices are not required as in the technique of Patent Document 3. Therefore, the mold release property of the injection molding apparatus can be improved with a simple structure and method.
Here, the elastic member is preferably a member that does not shorten to a predetermined load but shortens when the predetermined load is exceeded. Specifically, a member that is not shortened with respect to a predetermined load capable of releasing the biting of the reinforcing rib but is shortened when the extruded plate reaches the upper end and exceeds the predetermined load is preferable. For example, a gas spring containing a predetermined compressed gas (nitrogen gas) is suitable for the elastic member.

(7) The reinforcing rib extruding device described in (6) is characterized in that gas in the reinforcing rib cavity is allowed to escape from the sliding portion of the rib extruding pin. Can be prevented.
That is, since the rib push pin slides through the through hole formed in the reinforcing rib mold, a clearance of about 0.05 mm is provided between the push pin outer periphery and the through hole. And since it is this degree of clearance, the molten resin which has predetermined | prescribed viscosity is not leaked, releasing the gas in the cavity for reinforcement ribs.
Therefore, after the injection molding, the reinforcing ribs are extruded, and the resin parts for the vehicle can be taken out from the injection molding apparatus without deforming the panel main body, and molding such as lacking due to residual gas in the cavity for the reinforcing ribs. Defects can be reduced.

It is a perspective view of the resin component for vehicles (the 1st example) formed by the injection molding device concerning this embodiment. It is a back surface perspective view in the A section of FIG. It is a perspective view of the reinforcement rib in the B section of FIG. It is a back surface perspective view of the resin component for vehicles (2nd Example) shape | molded with the injection molding apparatus which concerns on this embodiment. It is a perspective view of the reinforcement rib in the E section of FIG. It is typical sectional drawing of the injection molding apparatus which concerns on this embodiment. FIG. 6 is a perspective view of a telescopic structure for forming the reinforcing rib shown in FIG. 5. It is sectional drawing of the reinforcement rib extrusion apparatus in FIG. FIG. 9 is a cross-sectional view of the reinforcing rib extrusion apparatus in FIG. 8 at a stage where the reinforcing rib extrusion is completed. FIG. 9 is a cross-sectional view of the panel main body lift completion stage in the reinforcing rib extrusion device of FIG. 8. It is a fragmentary perspective view of the rib extrusion pin which extrudes the general part of a reinforcement rib. It is sectional drawing of the cylindrical body extrusion apparatus which extrudes the cylindrical body of the reinforcement rib shown in FIG.

  Next, an injection molding apparatus and a reinforcing rib extrusion apparatus which are embodiments according to the present invention will be described in detail with reference to the drawings. First, the structure of the resin component for vehicles (the 1st example and the 2nd example) formed by the injection molding device concerning this embodiment and the detailed structure of a reinforcing rib are explained. Next, a description will be given of the nested structure for molding the stepped reinforcing rib of the injection molding device and the vehicle resin part (second example) according to the present embodiment. Finally, the structure and operation of the reinforcing rib extrusion device will be described.

<Structure of resin part for vehicle (first embodiment)>
First, the structure of a vehicular resin part (first example) molded by an injection molding apparatus according to an embodiment of the present invention will be described using an example of a bumper (semi-finished product). FIG. 1 is a perspective view of a bumper (semi-finished product) that is a resin component for a vehicle (first embodiment) molded by an injection molding apparatus according to the present invention.

As shown in FIG. 1, a bumper 10 that is a resin component for a vehicle (first embodiment) has a substantially U-shape in which left and right ends are curved in the vehicle side surface direction. The upper end 13 of the bumper 10 is formed with a parting part with a radiator grill or a fender. The panel body 1 of the bumper 10 is formed with a license plate mounting seat (near the center) and fog lamp mounting holes (both sides). Except for the mounting seats and mounting holes for these other parts, the outer surface (the surface side of the panel body) along the outside of the vehicle serves as a design surface, and is molded with an emphasis on appearance quality (appearance).
In order to increase the resin fluidity at the time of injection molding, for example, a plurality of resin injection parts R1 to R6 are arranged on the panel body in order to ensure the appearance of the design surface, the reduction in the thickness of the component plate and the increase in the rigidity of the entire component. 1 are provided in the upper and lower ends 13, 14 and the fog lamp mounting hole 15. And resin injection | pouring part R1-R6 is removed after injection molding.
Further, in the panel main body 1, reinforcing ribs 2 described below are formed on the back side 12 of a portion having a small cross-sectional curvature (for example, part A).

<Structure of reinforcing rib in resin part for vehicle (first embodiment)>
Next, the structure of the reinforcing rib 2 projecting from the back side 12 of the panel body 1 in the vehicle resin component 10 (first embodiment) will be described. FIG. 2 is a rear perspective view of the portion A in FIG. FIG. 3 is a perspective view of the reinforcing rib in the portion B of FIG.

  As shown in FIG. 2, a plurality of reinforcing ribs 2 project from the back surface side 12 of the panel body 1 while intersecting each other. The reinforcing ribs 2 are formed over a predetermined range on the back surface side 12 of the panel main body 1 while intersecting radially to form a plurality of honeycomb shapes. The reinforcing rib 2 has a proximal end portion connected to the panel body 1 and a distal end portion opened. The proximal end portion and the distal end portion of the reinforcing rib 2 are formed with the same thickness.

  As shown in FIG. 3, flexure portions C and D including intersection portions 22 and 22 </ b> B where the reinforcing rib 2 intersects are formed on the back surface side 12 of the panel body 1. At the location of the bent portion C, the general portions 21 of the three reinforcing ribs 2 intersect at one location to form an intersecting portion 22. Moreover, in the location of the bending part D, the general part 21 of the three reinforcing ribs 2 intersects the cylindrical body 23 to form an intersecting part 22B. Therefore, on the back surface side 12 of the panel body, the bent portion C including the intersecting portion 22 where the general portion 21 of the reinforcing rib 2 intersects linearly, and the intersection where the general portion 21 of the reinforcing rib 2 intersects the cylindrical body 23. A loop shape (here, a honeycomb shape) is formed to be closed via the bent portion D including the portion 22B. In addition, the loop shape (honeycomb shape) which does not have the bending part D is also formed. Further, the thickness of the reinforcing rib 2 is about 1/3 or less of the thickness of the panel body 1.

<Structure of Resin Component for Vehicle (Second Example)>
Next, the structure of the vehicle resin part (second example) molded by the injection molding apparatus according to the embodiment of the present invention will be described with an example of a side mud guard (semi-finished product). FIG. 4 shows a rear perspective view of a vehicle resin part (second example) molded by the injection molding apparatus according to the present embodiment. FIG. 5 is a perspective view of the reinforcing rib in the E part of FIG.
As shown in FIG. 4, the side mudguard 10 </ b> A that is a resin component for a vehicle (second embodiment) is attached along the side surface of the vehicle and has substantially the same cross-sectional shape in the vehicle front-rear direction. The vehicle resin component 10 </ b> A includes a panel body 1, a reinforcing rib (hereinafter also referred to as “stepped reinforcing rib”) 2 </ b> A, a resin supply path 3, and a gusset rib 4. Here, the arrow X indicates the vehicle longitudinal direction, the arrow Y indicates the vehicle vertical direction, and the arrow Z indicates the vehicle width direction.
The panel main body 1 is a thin plate-like body including a general portion 16 having a small cross-sectional curvature, a curved portion 17 having a large cross-sectional curvature, and ridge lines 18 and 19 constituting a design surface. A plurality of stepped reinforcing ribs 2 </ b> A having an undercut shape formed on one side surface is erected on the back surface side 12 of the general portion 16. The ridge lines 18 and 19 correspond to a character line (18) in design, a parting line (19) of a component terminal, and the like. The parting line (19) is provided with a gate for supplying the molten resin into the cavity of the mold.

<Structure of reinforcing rib in resin component for vehicle (second embodiment)>
As shown in FIG. 4, the stepped reinforcing rib 2 </ b> A in the resin component for a vehicle (second embodiment) has a thickness of the base end portion 21 joined to the back surface side 12 of the panel body 1 and a thickness of the tip end portion 22. It is made thinner. The cross section of the stepped reinforcing rib 2A is substantially constant in the rib extending direction (direction of arrow X). The side end 23A, which is the end of the stepped reinforcing rib 2A (the direction of the arrow X), is open near the boundary of the general portion 16. The stepped reinforcing rib 2 </ b> A extends away from the ridge line portion 18 of the panel body 1 substantially in parallel. The stepped reinforcing rib 2 </ b> A is formed in a substantially linear shape in the rib extending direction (the direction of the arrow X), but can be greatly curved along the ridge line portion 18 of the panel body 1. The interval between the plurality of stepped reinforcing ribs 2A increases and decreases according to the cross-sectional curvature of the general portion 16 to be erected. If the cross-sectional curvature of the general portion 16 is reduced, the interval between the stepped reinforcing ribs 2A is reduced. If the cross-sectional curvature of the general portion 16 is substantially constant, the intervals between the stepped reinforcing ribs 2 </ b> A are approximately equal.

  As shown in FIG. 5, the thickness of the base side 212A of the base end portion 21A is formed to the minimum (ultra-thin) to a predetermined height (position of the alternate long and short dash line), and the upper end joined to the lower end 222A of the tip end portion 22A The thickness of the side 211A is formed slightly thicker than the thickness of the root side 212A. For example, the thickness of the base side 212A is preferably about 0.3 to 0.4 mm, and the thickness of the upper end side 211A is preferably about 0.4 to 0.6 mm. At this time, the height of the base end portion is about 3.0 mm, and the height of the base side 212 is about 0.5 mm.

  As shown in FIG. 5, the lower end 222A of the distal end portion 22A is formed in a taper shape so that the thickness gradually decreases toward the proximal end portion 21A. The inclination angle of the lower end 222A formed in a tapered shape with respect to the horizontal direction is preferably about 45 degrees. In order to increase the rigidity in the rib extending direction while reducing the weight, it is preferable to increase the thickness of the distal end portion 22A when the height is lowered and reduce the thickness when the height is increased. For example, when the height of the tip 22A is about 5.0 mm, the wall thickness is about 2.0 mm. Further, when the height of the tip 22A is about 3.0 mm, the wall thickness is about 3.0 mm.

As shown in FIG. 5, the upper end 221 </ b> A of the distal end portion 22 </ b> A is formed substantially parallel to the back surface side 12 of the panel body 1. A curved surface is formed at the upper end 221A of the tip 22A and the corner 223A that intersects the other side opposite to the one side where the undercut shape is formed. By forming a curved surface at the corner portion 223A, it is possible to guide the molten resin supplied from the resin supply path 3 described later to the distal end portion 22A so as to flow toward the base end portion 21A along the other side surface. it can.
A resin supply port 32 through which molten resin is supplied to the distal end portion 22A via the resin supply path 3 is formed at the lower end 222A of the distal end portion 22A.

The resin supply path 3 supplies the molten resin supplied from the gate shown in FIG. 4 into the mold cavity of the panel body 1 in advance of the base end 21A to the tip 22A of the stepped reinforcing rib 2A. It is a hot spring. The resin supply path 3 is formed along the proximal end portion 21A from the joint portion 31 with the back surface side 12 of the panel body 1 to the lower end 222A of the distal end portion 22A of the stepped reinforcing rib 2A, and is communicated with the resin supply port 32. Yes. The resin supply path 3 is formed in the rib height direction (the direction of arrow Z) by partially increasing the thickness of the base end portion 21A on the undercut side. The resin supply path 3 is formed at a predetermined interval in the rib extending direction (the direction of the arrow X), and when releasing from the mold after the injection molding, the resin supplying path 3 is orthogonal to the rib extending direction together with the stepped reinforcing rib 2A (arrow). Y direction).
The gusset rib 4 is a triangular reinforcing rib that connects the base side 212 </ b> A of the base end 21 </ b> A and the back side 12 of the panel body 1. The gusset ribs 4 are formed at predetermined intervals in the rib extending direction (the direction of the arrow X). The gusset rib 4 reinforces only the base side 212A of the base end portion 21A, thereby preventing deformation and distortion of the panel body 1 at the time of mold release after injection molding.

<Overall structure of injection molding device>
Next, the overall structure and operation of the injection molding apparatus 100 according to this embodiment will be described. FIG. 6 is a schematic cross-sectional view of the injection molding apparatus according to this embodiment.

As shown in FIG. 6, the injection molding apparatus 100 includes a movable mold 3, a fixed mold 4, a reinforcing rib forming mold 5 (5 </ b> A), an elevating device 6, and a reinforcing rib extrusion device 7.
The movable mold 3 has a core mold 31 having a molding surface on the upper surface 311 of the panel main body back side 12, a mold block 32 as a spacer member, and a mold base 33 attached to a molding machine (not shown). The upper end 311 of the core mold 31 is formed with a recess 312 over the range where the reinforcing rib 2 or the stepped reinforcing rib 2A is formed, and the reinforcing rib forming die 5 (5A) is inserted into the recess 312. Yes. A mold cooling flow path (cooling circuit) 34 is formed inside the core mold 31.

  As shown in FIG. 6, the reinforcing rib forming die 5 (5A) includes a reinforcing rib mold 51 (51A) and a reinforcing rib pushing device 7. The reinforcing rib extrusion device 7 is fastened to the lower end of the reinforcing rib mold 51 (51 </ b> A) by a mounting plate 73. A telescopic member 75 extends downward from the mounting plate 73 and is fixed to a lifting plate 62 of the lifting device 6 described later. A mold cooling flow path (cooling circuit) 52 (52A) is formed inside the reinforcing rib mold 51 (51A). Cavity mold 51 for reinforcing ribs (51A) is a zinc alloy casting (for example, ZAS (Mitsui Metal Mining Co., Ltd.) having high thermal conductivity and good machinability as compared with core mold and mold mold made of high-strength alloy steel. Product name)). The composition of the zinc alloy is, for example, that Al is about 4%, Cu is about 3%, Mg is about 0.05%, and the balance is Zn. The thermal conductivity is about 2.5 to 4 times higher than that of ordinary alloy steel.

As shown in FIG. 6, a lifting device 6 that lifts and lowers the panel body 1 is stored between the lower end 313 of the core mold 31 and the mold base 33. The elevating device 6 includes an elevating pin 61 that comes into contact with the panel body back side 12 at the upper end and a common elevating plate 62 that comes into contact with the lower ends of the plurality of elevating pins 61. The lifting plate 62 is in contact with the mold base 33 of the movable mold 3.
The raising / lowering pin 61 is arrange | positioned so that a highly rigid location may be raised / lowered among the panel main bodies 1. FIG. The lift plate 62 is moved up and down by a predetermined lift stroke length S2 (see FIG. 7) by a cylinder rod 9 of a molding machine (not shown) that moves forward and backward through the mold base 33. The stroke length S <b> 2 of the elevating device 6 is set so as to elevate the injection-molded vehicle resin part 10 (10 </ b> A) to a position where it can be removed from the core mold 31.

As shown in FIG. 6, the fixed mold 4 includes a mold 41 having a molding surface on the panel body surface side 11 at the lower end 411, a mold block 42 as a spacer member, and a mold base 43 attached to a molding machine (not shown). And have. A mold cooling flow path (cooling circuit) 44 is formed inside the mold 41.
The mold cooling channels (cooling circuits) 34, 44, 52 (52A) formed in the core mold 31, the cavity mold 41, and the reinforcing rib cavity mold 51 (51A) respectively constitute independent cooling circuits. doing. And it has the control part (not shown) which controls the temperature of each cooling circuit independently.

<Nested structure>
Next, a nested structure for molding the reinforcing ribs of the vehicle resin component (second embodiment) will be described. FIG. 7 shows a perspective view of a nested structure for forming the reinforcing rib shown in FIG.
As shown in FIG. 7, a reinforcing rib cavity mold 51 </ b> A having a rectangular nested structure is inserted into the core mold 31. In the reinforcing rib cabinet 51A, rectangular rib grooves 51a, 51b, 51c are formed at positions corresponding to the stepped reinforcing rib 2A. Slide pieces 53 (53a, 53b, 53c) having a substantially L-shaped cross section are inserted in the rib grooves 51a, 51b, 51c so as to be movable up and down. The slide piece 53 (53a, 53b, 53c) is connected to an elevating plate 62 (see FIG. 6) of the elevating device 6 via an elastic member (not shown). The slide piece 53 (53a, 53b, 53c) can absorb the resin shrinkage during the injection molding of the stepped reinforcing rib 2A through the elastic member.

Here, gaps between the rib grooves 51a, 51b, 51c formed in the reinforcing rib mold 51A and the slide pieces 53a, 53b, 53c constitute a cavity of the stepped reinforcing rib 2A. Therefore, the thickness of the stepped reinforcing rib 2A can be easily changed by adjusting the gap. In particular, it becomes easy to set the thickness of the base end portion 21A to be thin.
In the reinforcing rib mold 51A, a mold cooling flow path (cooling circuit) 52A is provided at a position where it does not interfere with the rib grooves 51a, 51b, 51c. The passages (cooling circuits) 34 and 44 are formed independently.

As shown in FIG. 7, cavities 53ag, 53bg, and 53cg of the resin supply passage are formed at predetermined intervals at the upper ends of the slide pieces 53a, 53b, and 53c. Cavity 53ah, 53bh, and 53ch of gusset ribs are formed at predetermined intervals at the upper ends of the slide pieces 53a, 53b, and 53c. The resin supply passage cavities 53ag, 53bg, 53cg and the gusset rib cavities 53ah, 53bh, 53ch are all narrow grooves, but the slide pieces 53a, 53b, 53c can be taken out of the reinforcing rib mold 51A and processed. Therefore, workability is improved.
Moreover, the cavity of a gusset rib can also be formed in the shoulder of the rib groove | channels 56a, 56b, 56c formed in 51 A of reinforcing rib cabinet types.

<Reinforcement rib extrusion device>
Next, the reinforcing rib extrusion device 7 for extruding the reinforcing rib 2 from the reinforcing rib mold 51 will be described. FIG. 8 shows a cross-sectional view of the reinforcing rib extrusion apparatus in FIG. FIG. 9 shows a cross-sectional view of the reinforcing rib extrusion completion stage in the reinforcing rib extrusion apparatus of FIG. FIG. 10 shows a cross-sectional view of the panel body assembling completion stage in the reinforcing rib extrusion apparatus of FIG. In FIG. 11, the fragmentary perspective view of the rib extrusion pin which extrudes the general part of a reinforcement rib is shown.

As shown in FIG. 8, the reinforcing rib extruding device 7 includes a rib extruding pin 71, a first extruding plate 72, a mounting plate 73, a connecting rod 74, a telescopic member 75, a guide pin 76, and a compression spring 77.
The rib extruding pin 71 is a rod-like extruding pin having a diameter larger than the thickness of the reinforcing rib 2 and slides in a through-hole 513 formed in the reinforcing rib mold 51. The gap between the rib extruding pin 71 and the through hole 513 is about 0.05 mm, and serves as a gas vent passage during molding.
Further, as shown in FIG. 11, at the upper end of the rib push pin 71, a first contact portion 711 that contacts the general portion 21 of the reinforcing rib 2 and a second contact portion 712 that contacts the side wall of the reinforcing rib 2. And a third abutting portion 713 that abuts against the panel main body back side 12. The rib extruding pin 71 improves the releasability by directly extruding the reinforcing rib 2. Note that the second contact portion 712 has a function of preventing the reinforcing rib 2 from bending in the lateral direction when the reinforcing rib 2 is pushed out.

  As shown in FIG. 8, the first extruded plate 72 is accommodated in a recess 512 formed at the lower end of the reinforcing rib mold 51. The lower part of the rib push pin 71 is locked to the first push plate 72. A predetermined gap is provided between the upper end of the recess 512 of the reinforcing rib mold 51 and the first extrusion plate 72. At the time of pushing out the reinforcing rib, the rib pushing pin 71 and the first pushing plate 72 move through the predetermined gap, and the first pushing plate 72 comes into contact with the upper end of the recess 512 of the reinforcing rib mold 51 and stops. Spring seats 722 and 514 are formed in the upper end of the first push plate 72 and the upper end of the recess 512 of the reinforcing rib mold 51, and a return compression spring 77 is inserted therebetween.

As shown in FIG. 8, the mounting plate 73 is fastened to the lower end of the reinforcing rib mold 51. A guide pin 76 is erected between the upper end of the mounting plate 73 and the upper end of the recess 512 of the reinforcing rib mold 51, and the movement of the first push plate 72 is guided by the guide pin 76. Before pushing out the reinforcing ribs, the first pushing plate 72 is in contact with the upper end of the mounting plate 73.
The connecting rod 74 is disposed at the lower end of the first push plate 72. At the upper end of the connecting rod 74, a flange portion 741 is provided. The flange portion 741 is in contact with the lower end of the first push plate 72. The core mold 31 is provided with a through hole 314 through which the connecting rod 74 is inserted.

As shown in FIG. 8, the elastic member 75 includes a first extrusion cylinder rod 751 and a first extrusion cylinder case 752. The first extrusion cylinder rod 751 is connected to the connection rod 74. The lower end of the first extrusion cylinder case 752 is fixed to the lifting plate 62 of the lifting device 6.
The expansion / contraction member 75 is a gas spring, and a compressed gas (nitrogen gas) is incorporated in the first extrusion cylinder case 752. The compressed gas pressure is larger than the force of the compression spring 77 and the die biting force of the reinforcing rib 2, and after the first pushing plate 72 comes into contact with the upper end of the recess 512 of the reinforcing rib mold 51 and stops, the first pushing cylinder The rod 751 is set to be accommodated in the first extrusion cylinder case 752.

  As shown in FIG. 9, as the lifting plate 62 is raised, the reinforcing rib pushing device 7 rises as a whole, but the first pushing plate 72 comes into contact with the upper end of the recess 512 of the reinforcing rib mold 51. ,Stop. The stroke length S <b> 1 at this time is such that the reinforcing rib 2 is separated from the groove 511 of the reinforcing rib mold 51. In the first extruded cylinder case 752, a compressed gas (nitrogen gas) that can resist the biting force of the compression spring 77 and the reinforcing rib 2 is built in. Therefore, at this stage, the first extruded cylinder rod 751 is It is not stored in the first extrusion cylinder case 752.

  As shown in FIG. 10, when the elevating plate 62 is further raised, the first extrusion plate 72 is in contact with the upper end of the concave portion 512 of the reinforcing rib mold 51, so that the first extrusion cylinder rod 751 is in the first extrusion cylinder case. It is stored in 752. Therefore, the further elevating of the elevating plate 62 corresponds to the expansion / contraction member 75 being shortened. In addition, by the further raising of the raising / lowering plate 62, the injection-molded vehicle resin component 10 can be raised and lowered to a position where it can be taken out from the core mold 31. At this time, since the raising / lowering pins 61 are arranged so as to move up and down a highly rigid portion in the panel body 1, there is no possibility of problems such as deformation and whitening of the panel body 1.

<Cylinder Extruder>
Next, the cylindrical body extruding apparatus 8 that extrudes the cylindrical body 23 formed at the intersecting portion 22B of the reinforcing rib 2 will be described. FIG. 12 shows a cross-sectional view of a cylindrical body extruding apparatus that extrudes the cylindrical body of the reinforcing rib shown in FIG.
As shown in FIG. 12, the cylindrical body extruding device 8 includes an annular extruding pipe 81, a core member 82, a second extruding plate 83, and a second extruding cylinder 84.
The annular extruded pipe 81 is a pipe that has a tip portion having substantially the same diameter as the cylindrical body 23 and presses the lower end of the cylindrical body 23 to extrude it from the reinforcing rib mold 51 groove. The lower end of the annular extruded pipe 81 is fastened to the second extruded plate 83. A second extrusion cylinder 84 is disposed at the lower end of the second extrusion plate 83 and moves up and down the second extrusion plate 83. The second extrusion cylinder 84 is fixed to the mold stage 33 of the movable mold 3. The core member 82 is a rod-like body that forms a hollow portion on the inner peripheral side of the cylindrical body 23, and also serves as a guide member for the annular extruded pipe 81 and the second extruded plate 83. The lower end of the core member 82 is fixed to the mold base 33 of the movable mold 3. A gap between the core member 82 and the annular extruded pipe 81 is about 0.05 mm, and serves as a gas vent passage for the reinforcing rib cavity mold 51 groove.
Although the cylindrical body extrusion device 8 is provided as necessary, the extrusion load is distributed to the reinforcing rib 2 adjacent to the cylindrical body 23 to reduce the pushing load acting on the panel body 1 and the reinforcing rib 2 one by one. it can. Therefore, providing the panel body 1 at a location where the sectional curvature of the panel body 1 is small and the rigidity of the panel body 1 is small is effective in reducing deformation and whitening of the panel body 1.

<Effect>
As described above in detail, the injection molding apparatus 100 according to the present embodiment includes the mold mold 41, the core mold 31, and the reinforcing rib mold 51 (51A), and the reinforcing rib mold 51 ( 51A) is nested in the core mold 31, and therefore, the cooling circuit 52 (52A) of the reinforcing rib cavity mold 51 (51A) is provided separately from the cavity mold 41 and the cooling circuits 44 and 34 of the core mold 31. Is easy. In addition, since the reinforcing rib mold 51 (51 A) is nested in the core mold 31, it is easy to block the transmission of mold temperature between the reinforcing rib mold 51 (51 A) and the core mold 31. . Further, since the cooling circuit 52 (52A) of the reinforcing rib cavity mold 51 (51A) is controlled independently of the cooling circuit 44, 34 of the cavity mold 41 and the core mold 31, the panel body 1 and the reinforcing rib 2 as a whole. Even when the wall thickness of the reinforcing rib 2 is reduced, the reinforcing rib cavity mold 51 (51A) can be set to the optimum cooling temperature for the thickness of the reinforcing rib 2 (2A) without causing sinking of the panel body 1 or the like. The solidification time of the panel body 1 and the reinforcing rib 2 (2A) can be shortened.

  Further, according to the present embodiment, the mold cooling temperature of the reinforcing rib mold 51 (51A) is higher than the mold cooling temperatures of the mold 41 and the core mold 31, and therefore the reinforcing rib mold 51 is used. By controlling the cooling temperature of (51A) so as to suppress the molding shrinkage of the reinforcing rib 2 (2A), the releasability of the reinforcing rib 2 (2A) can be improved. That is, by making the temperature on the reinforcing rib side higher than the temperature on the panel body side at the time of mold release, the molding shrinkage amount of the reinforcing rib 2 (2A) is relatively reduced compared to the molding shrinkage amount of the panel body 1. Can be made. By providing a difference in the amount of molding shrinkage between the reinforcing rib 2 (2A) and the panel body 1, it is possible to reduce the mold biting of the reinforcing rib 2 (2A) and improve the releasability. The cooling temperature of the reinforcing rib mold 51 (51A) is preferably about 50 ° C., and the cooling temperature of the mold 41 and the core mold 31 is preferably about 20 ° C.

Further, according to the present embodiment, the reinforcing rib mold 51 (51A) is characterized by being formed by grooving a zinc alloy casting having a higher thermal conductivity than the mold 41 and the core 31. The mold temperature of the reinforcing rib cavity mold 51 (51A) is substantially uniform as a whole without being affected by the mold temperatures of the cavity mold 41 and the core mold 31, and the thickness is reduced while preventing the design surface from sinking. The releasability of the vehicle resin component 10 (10A) can be further improved.
Further, since the reinforcing rib mold 51 (51A) is a zinc alloy casting, the machinability is greatly improved compared to the high-strength alloy steel generally used for the mold 41 and the core 31. For example, groove processing for reinforcing ribs having a width of about 0.5 mm and a depth of about 5.0 to 6.0 mm can be performed using an end mill. Therefore, it is possible to easily manufacture the reinforcing rib mold 51 (51A) for realizing the ultra-thinning of the reinforcing rib 2 (2A).

Moreover, according to this embodiment, the lifting / lowering apparatus 6 which raises / lowers the panel main body 1 and the reinforcement rib extrusion apparatus 7 which extrudes the reinforcement rib 2 are provided, and the extrusion stroke length of the reinforcement rib extrusion apparatus 7 is raised / lowered of the elevation apparatus 6. Since the length is equal to or shorter than the stroke length, the reinforcing rib pusher 7 is sufficient to push the reinforcing rib 2 out of the reinforcing rib mold 51 groove. Further stroke lengths can be assigned to the removal stroke length after molding so that the lifting device 6 that lifts and lowers the panel body 1 plays its role. Therefore, even if the diameter of the rib extruding pin 71 that extrudes the thinned reinforcing rib 2 is small, the stroke length is short, so that problems such as breakage of the rib extruding pin 71 are unlikely to occur.
Further, since the reinforcing rib extruding device 7 is released by directly extruding the reinforcing rib 2, it is possible to effectively release the mold biting of the reinforcing rib 2, and the panel main body 1 is deformed or whitened. There is little possibility of causing problems such as.

  Moreover, according to this embodiment, the cylindrical body 23 is formed in the crossing part 22B of the reinforcing rib 2, and the cylindrical body extruding device 8 for extruding the cylindrical body 23 is provided. The extrusion load is dispersed on the reinforcing rib 2 adjacent to the portion 22B, and the extrusion load acting on the panel body 1 and the reinforcing rib 2 can be reduced. As a result, even if the panel body 1 and the reinforcing rib 2 as a whole are further thinned, the risk of problems such as deformation and whitening of the panel body 1 and the reinforcing rib 2 during mold release can be further reduced. it can.

Further, according to the reinforcing rib extruding device 7 used in the injection molding apparatus 100 according to the present embodiment, the first extruding plate 72 that holds the rib extruding pin 71 so as to be movable up and down is first extruded as the elevating plate 62 rises. After the plate 72 reaches the upper end, the elastic member 75 is shortened by further raising of the elevating plate 62, so that the rib extruding pin 71 directly extrudes the reinforcing rib 2 to improve the releasability while extruding the rib. The stroke length of the pin 71 can be shortened by shortening the elastic member 75. Since the stroke length of the rib extruding pin 71 is shortened, problems such as breakage, bending, and galling of the rib extruding pin 71 can be reduced.
Moreover, since it is only necessary to provide the expansion / contraction member 75 between the raising / lowering plate 62 of the raising / lowering apparatus 6 and the 1st extrusion board 72, a several measurement detection mechanism and control apparatus are not required like the technique of patent document 3. FIG. . Therefore, the mold release property of the injection molding apparatus can be improved with a simple structure and method.

Further, according to the present reinforcing rib extruding device 7, since the gas in the reinforcing rib cavity is released from the sliding portion of the rib extruding pin 71, the reinforcing rib 2 has defects such as lacking and welds. Can be prevented.
That is, since the rib push pin 71 slides through the through hole 513 formed in the reinforcing rib mold 51, a clearance of about 0.05 mm is provided between the rib push pin outer periphery and the through hole. It has been. And since it is this degree of clearance, the molten resin which has predetermined | prescribed viscosity is not leaked, releasing the gas in the cavity for reinforcement ribs.
Therefore, the reinforcing rib 2 is extruded after the injection molding, and the vehicle resin part 10 can be taken out from the injection molding apparatus 100 without deforming the panel main body 1 and the lack of gas in the reinforcing rib cavity remains. Molding defects such as meat can be reduced.

This embodiment mentioned above can be changed in the range which does not change the summary of this invention.
In the present embodiment, the reinforcing rib mold 51 (51A) is formed by grooving a zinc alloy casting having a higher thermal conductivity than the mold 41 and the core mold 31 with an end mill. However, the grooving method need not be limited to cutting by an end mill.
For example, grooving using electric discharge machining is also possible. In the case of a zinc alloy casting, the machined surface is not hardened even by electric discharge machining, and subsequent polishing can be performed smoothly. Moreover, if it is electrical discharge machining, the effect which can process the thickness and external shape of a reinforcement rib freely is also show | played.

  INDUSTRIAL APPLICABILITY The present invention can be used as an injection molding apparatus for injection molding of vehicle resin parts used for interior and exterior parts such as automobile bumpers and trims, and a reinforcing rib extrusion apparatus used for the injection molding apparatus.

DESCRIPTION OF SYMBOLS 1 Panel main body 2 Reinforcement rib 2A Stepped reinforcement rib 3 Movable type 4 Fixed type 5 Reinforcement rib molding die 5A Reinforcement rib molding die 6 Lifting device 7 Reinforcement rib extrusion device 8 Cylindrical body extrusion device 10 Resin parts for vehicles (bumper)
10A Resin parts for vehicles (side mudguard)
21 General portion of reinforcing rib 21A Base end portion of stepped reinforcing rib 22A Tip end portion of stepped reinforcing rib 23 Tubular body 31 Core type 41 Cavity type 51 Cavity type for reinforcing rib 51A Cavity type for reinforcing rib 52 Cavity for reinforcing rib Mold flow path (cooling circuit)
52A Cavity-type flow path for cooling rib (cooling circuit)
53 Slide Piece 71 Rib Extrusion Pin 75 Elastic Member 81 Annular Extrusion Pipe 100 Injection Molding Device

Claims (7)

An injection molding apparatus for a resin component for a vehicle in which a plurality of reinforcing ribs project from the back side of the panel body,
A cavity mold, a core mold, and a reinforcing rib cabinet mold, wherein the reinforcing rib cabinet mold is nested in the core mold;
2. The injection molding apparatus according to claim 1, wherein the reinforcing rib mold has a cooling circuit controlled independently of the cooling mold and core cooling circuits. In the injection molding device according to claim 1,
An injection molding apparatus, wherein a mold cooling temperature of the reinforcing rib cabinet mold is higher than mold cooling temperatures of the mold mold and the core mold. In the injection molding apparatus according to claim 1 or 2,
2. The injection molding apparatus according to claim 1, wherein the reinforcing rib mold is formed by grooving a zinc alloy casting having a higher thermal conductivity than the mold mold and the core mold. The injection molding device according to any one of claims 1 to 3,
An elevating device for elevating and lowering the panel body, and a reinforcing rib pushing device for extruding the reinforcing rib,
An injection molding apparatus, wherein an extrusion stroke length of the reinforcing rib extrusion device is set to be equal to or less than an elevation stroke length of the lifting device. The injection molding device according to any one of claims 1 to 4,
A cylindrical body is formed at the intersection of the reinforcing ribs, and an injection molding apparatus comprising a cylindrical body extruding device for extruding the cylindrical body. A reinforcing rib extrusion device for use in the injection molding device according to claim 4,
A rib extruding pin that contacts the general portion of the reinforcing rib;
An extruding plate that holds the rib extruding pin up and down; and
A telescopic member that expands and contracts between the lifting plate of the lifting device and the extrusion plate;
The reinforcing rib extruding device according to claim 1, wherein after the push-out plate reaches the upper end as the elevating plate rises, the stretchable member is shortened by further raising of the elevating plate. In the reinforcing rib extrusion device according to claim 6,
A reinforcing rib extruding apparatus characterized in that gas in the reinforcing rib cavity escapes from a sliding portion of the rib extruding pin.

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