JP2003039495A - Mold for injection-molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold for injection-molding capable of realizing the simultaneous filling of each cavity with a molten resin while keeping the fluidity and/or the uniformity of a resin pressure of the molten resin flowing from a sprue of the multi-cavity mold for an identical molded product to each cavity and the molten resin in each cavity. SOLUTION: Curvature runners 5a and 5b with a curvature center placed on the cold slug well 4c and 4e side as fluidity adjusting runners, are formed between flow path change points 11b and 11c and runners 3c and 3e on the side where the molten resin flows out of the flow path change points 11b and 11c. Consequently, the fluidity and the concurrent filling properties of the molten resin into the cavities 7a to 7h, especially the fluidity and the concurrent filling properties into the cavities 7b, 7c (7f and 7g) are upgraded. Thus it is possible to provide the molded product with a presentable appearance and high-strength while preventing a short shot, a weld line or burrs from occurring and the mold whose remodeling cost is low.

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention
The multi-cavity injection molding die
Molten resin introduced into cavity and melting in each cavity
To make the resin fluidity and / or resin pressure uniform
This is related to a runner shape. [0002] 2. Description of the Related Art Runners are molten trees from sprues to gates.
Flow path to guide oil, especially loss of flow pressure in runner
Loss is required to be very small,
The shape of the runner, such as the surface and the length of the flow path,
This is an operational challenge. [0003] Especially in a multi-cavity mold of the same molded product
Is that each cavity is filled with molten resin at the same time.
As shown in Fig. 3, the filling
It is arranged to take a lance,
The flow distance to the point is equal and as short as possible
Is taken into account. In addition, depending on the heating mode of the runner,
Cold runner type and hot runner type
Be classified. Cold runners are generally mold parts.
Formed on the running surface and more rapidly than around the runner
Cooling increases flow resistance in the runner and increases
Injection pressure is required. Hot runner against this
Can bury an electric heater outside the runner or
ー Cavity is formed in the periphery and high-temperature heat medium oil is flowed and heated
By using the heat insulation of the molding material
By insulated runner without head heating
Always maintains the molten state of the resin, reducing flow resistance
At the same time, material loss and secondary processing are reduced. This
Hot runners require complex and expensive heating equipment
Cold runners except for mass production
-Is the mainstream. [0005] By the way, the same as described above.
In a multi-cavity mold of one molded product, the melt in the runner
At the branch point or flow path change point of the molten resin,
Not to flow into the cavity by housing
As such, cold slug wells are commonly provided. FIG. 3 shows a conventional example, which is generally adopted.
Cavity 7 in mold 20 for taking eight identical moldings
_ahAnd Cold Slagwell 4_{a to f}Orchid with
Gnar 3 _{a to f}FIG. Cap
Vity 7_ahAnd runner 3_{a ~ F}The shape is filled balun
Take cavity 7_ahFilling at the same time
As shown in the figure, the flow direction of the sprue 2 is vertically symmetric
And also runner 3_c, 3_eThe vertical flow direction of
Are arranged symmetrically in the figure, and
The flow distance to the gate 6 is equidistant and as short as possible.
It is taken into consideration. As in this conventional example, the shape of the runner is shown in FIG.
In general, the shape shown in FIG.
To make it easier for the molten resin to flow to the runner connection.
Cold Slagwell 4_c, 4_eFrom the opposite side
Curvature runner 8 with center of curvature_a, 8_bBig as
Some have great curvature. However, in the above-mentioned conventional example, the strict
, The inertia of the flow remains in the direction of the arrows in FIGS. 4 and 5.
Cavities because of the effects of flow momentum.
I7 _aAnd 7_b(7_eAnd 7_f7) more than groups_cAnd 7_d
(7_gAnd 7_h) Tends to flow in the direction of the group
And cavity 7_b(7_f7) than_a(7_e)
, 7_c(7_g7) than_d(7_h)
Tend to. Specifically, the cavity 7_bAnd 7_c(7_f
And 7_g) Is a little short shot
But a weak weld line is generated. Conversely, the show
To prevent the shot from coming out, the cavity 7_a(7
_e) And 7_d(7_h) Becomes burrish. This tendency is due to continuous molding of good products.
Although latent, it is not a problem in general molding. However, the multi-cavity 7
_ahDifferences in fluidity and resin pressure
This can result in significant defects in the molded article. For example, people
When it comes to molding critical security parts for cars that can be life-threatening
This is an example. The present invention has been made in view of the above circumstances.
From the sprue of a multi-cavity mold of the same molded product.
Activity 7_ahImproved simultaneous filling of molten resin up to
Let the cavity 7_ahFlow and Resin Pressure of Molten Resin
To provide injection molds that ensure uniformity of force
Make it an issue. [0013] Means for Solving the Problems To solve the above problems,
The features of the present invention relating to the molding die
Transfers molten resin injected from the resin inlet
And a plurality of runners from the sprue.
That are arranged at the same distance from each other and form the same molded product
Extends beyond the cavity and the runner channel change point
Injection molding having a cold slag well provided
In the multi-cavity molding die of the forming machine,
And the flow of the molten resin in each cavity communicating with the runner.
Flow paths to ensure dynamic and / or resin pressure uniformity
The change point and the line on the side where the molten resin flows out from this flow path change point
The angle of the molten resin outflow direction is
Flow direction of molten resin returning from slag well to channel change point
A flow control runner larger than 90 °
And there. According to the present invention, with this configuration,
The point where the molten resin changes the flow direction while flowing in the runner
Flow path defined as
Outflow of molten resin between the resin and the runner on the outflow side
Direction angle returned from cold slug well to flow change point
Greater than 90 ° to the flow direction of the molten resin
Runner smaller than ° (hereinafter referred to as flow control runner)
) Formed and returned molten tree from cold slag well
When the resin and the subsequent molten resin join, the subsequent molten
Returning flow momentum of fat from cold slag well
By holding down by the flow of the resin,
Flowability and / or tree of molten resin
Since the grease pressure is made uniform, each cavity
While maintaining simultaneous filling into the cavity,
Flowing and uniform resin pressure in each cavity
It becomes. Therefore, with this method, there is no unevenness.
High-quality, high-strength, high-quality non-defective products simultaneously
The purpose is to provide a mold for injection molding that can
You. The shape of the flow control runner has a curvature.
Runner (hereinafter referred to as curvature runner), polygon
Runner (hereinafter called polygon runner), straight
Runners are devised. [0015] Embodiments of the present invention will be described below.
This will be described in detail with reference to the drawings. FIG. 1 shows an embodiment of the present invention.
Of Parting Injection Mold in Vertical Form
FIG. Fig. 2 shows the flow of the resin flowing through the channel change point and the branch point.
It is a figure showing a moving state. 1 and 2 show an embodiment of the present invention.
In the form, as a flow control runner, the flow characteristics of the resin and
A curvature runner is adopted because of easy processing of the mold. still,
The resin used in the embodiment of the present invention is PMMA (Polymer).
Methyl methacrylate), PE (polyethylene), PP
(Polypropylene), thermoplastic resin such as ABS or
Thermosetting of melamine resin, phenol resin, epoxy resin, etc.
Resins, i.e., various known synthetic resin materials,
Will be adopted as appropriate. The mold 10 in FIG. 1 is a cold runner
It is a mold of the same type, and it is a mold for taking eight identical molded products. this
Heat injected from the injection nozzle 1 to the resin injection port of the mold 10
The plastic molten resin passes through the sprue 2 and turns to the branch point 9._{a to c}
And the flow path change point 11_{a ~ C}Change the flow path with
Gnar 3_{a to f}And curvature runner 5_a, 5_bVia each
Gate 6 to cavity 7_ahAt the same time.
At the end of the flow direction of the molten resin,
Houses gas and residual foreign substances contained in fat and
Cold slug well 4 to prevent inflow
_{a to f}Is arranged. Further, the mold 10 according to the present invention has a good filling balance.
Considering cavity 7_ah, Runner 3_{a to f}, Song
Rate runner 5_a, 5_b, Gate 6, cold slugwe
Le 4 _{a to f}Is the upper direction in FIG. 1 with respect to the flow direction of the sprue 2.
Symmetrically and runner 3 _cAnd 3_eFlow up and down
1 are symmetrically arranged in FIG.
Flow distance L from the gate 2 to each gate 6_1-5Is the shortest, etc.
It is configured to be distance. By the way, the curvature runner 5_a, 5_bCurvature
Cold slag well 4 in the center_c, 4_eFrom the side, i.e.
The angle of the outflow direction of the molten resin is cold slag well 4_c,
4_eTo channel change point 11_b, 11_cOf molten resin back to
The reason for taking more than 90 ° to the moving direction is shown in FIG.
As you did, Cold Slagwell 4_c, 4_eBounce off
When the returned molten resin merges with the subsequent molten resin
(See the arrow in the figure)
Cold Slagwell 4_c, 4_eReturn melting back
By holding down by the flow of resin, the sprue 2
Vity 7_ahOf the molten resin introduced into the
Alternatively, the resin pressure is made uniform and the cavity 7_ahTo
Make the cavity flow evenly_ahResin inside
The purpose is to equalize the pressure. Therefore, the curvature runner 5
_a, 5_bHere is a numerical value for the magnitude of the curvature of
No, but runner 3_{a to f}The shape and length of the resin used
Consider the flow characteristics, temperature characteristics of the mold and resin used, etc.
Is determined. In addition, runner 3_{a to f}And
Vity 7_ahFlow speed of upstream and downstream resin flowing inside
Runner 3_{a to f}And cavity 7
_ahSince the upstream and downstream resin pressures inside the
-3_{a to f}And cavity 7_ahResin tree flowing inside
The grease pressure cannot be equalized, but the runner 3
_{a to f}And cavity 7_{a ~ H}The resin pressure in the chamber
This means that runners are symmetrically arranged
3_{a to f}Each other and cavity 7_ahFrom sprue 2 in
Equalizing resin pressure during flow at the same distance
It means. Next, the flow of the resin in the mold 10 will be described.
You. The molten resin injected from the nozzle 1 passes through the sprue 2
Cold slag well 4_aAt the junction 9
_a, And runner 3_aThrough the cold slug
Well 4_bFlow in the direction. Flowed molten resin is coal
Dosragwell 4_bBounce back in the molten resin and subsequent
Flow path change point 11 with molten resin_aMerge at and runner 3_b
Through the cold slug well 4_cFlow in the direction. This
In this case as well, the molten resin that has flowed
Le 4_cThe molten resin that bounces back and the subsequent molten resin
Channel change point 11 _bMerge at and runner 3_cFlow of resin inside
Curvature runner 5 set to have uniform mobility_aTo
Through the cold slag well 4_dFlow in the direction. Soshi
And runner 3_cThe resin that has flowed through
Lugwell 4_dAt the junction 9_bEvenly with
Sink, runner 3_dThrough the cold slug well 4_e
Flow in the direction. Furthermore, the molten resin that has flowed
Lugwell 4_eThe molten resin bounced back and the subsequent melting
Channel change point 11 with resin_cMerge at and runner 3_eInside
Curvature runner set for uniform resin flow
-5_bThrough the cold slug well 4_fFlow in the direction
You. And runner 3_eThe resin flowing through
Old Slagwell 4_fAt the junction 9_cso
Divide evenly, runner 3_fThrough each gate 6
Activity 7_ahAt the same time. The curvature runner
5_a, 5_bThe curvatures need not be the same.
As mentioned above, the numerical values are not specified, but
Gnar 3_{a to f}Consider the shape and length of the
It is decided in consideration. In the embodiment of the present invention, another runner 3 is used.
_cfRunner 3 than the flow path length of_bFlow path length
Channel change point 11_aMolten tree flowing into
The effect of the inertia of the fat flow is_bFlowing inside
Flow point is changed because the fluidity is reduced and the fluidity becomes uniform.
1_aCold slag well 4_bHas a center of curvature from
There is no particular need to provide a curvature runner. If runner
3_bIf the fluidity of the
To improve the liquidity. Next, in this embodiment, 1) injection of molten resin
At the entrance, it has a circular cross section of 3 mm in diameter and has a branch point 9_aIn diameter
Sprue 2 with a 3.5 mm circular cross section, 2) diameter
3.5mm semi-circular cross section and 1mm short axis 3.5mm long axis
Add a half-elliptical cross-section in the minor axis direction of the ellipse
Runner 3 with cross section_aAnd 3) mold party
3.5mm diameter with cold runner formed on the bearing surface
3 having a semicircular cross section of_b, 3_c, Coldos
Lugwell 4_b,4_c,Curvature run with radius of curvature 2.5mm
Gnar 5_aAnd a semi-circular section having a diameter of 2.5 mm
Inner 3_d, 3_e, 3_f, Cold slug well 4_d,
4_e,4_f,Curvature runner 5 with radius of curvature 5.0mm
_bAnd 4) Runner 3_fA circular section with a diameter of 1.0 mm on the side
Cavity 7 on the surface _ah0.8 mm diameter circular cross section
And a 1.0 mm long submarine gate 6 and 5)
Cavity 7 with 13 mm diameter circular cross section and 5 mm height
_ahAnd the center of the flow direction of the sprue 2 and
Runner 3_bDistance L between the centers in the flow direction ₁= 54mm,
Runner 3_bFlow direction center and runner 3_dFlow of
Center-to-center distance L₂= 6mm, runner 3_dFlow direction
Center and runner 3_fDistance L between the centers in the flow direction₃= 10
mm, runner 3_aFlow direction center and runner 3_cof
Flow direction center distance L₄= 94mm, runner 3_eof
Flow direction center distance L₅= 50mm, runner 3_fof
Using a mold having a distance of 18 mm between the gates 6, P
Injection molding with P (polypropylene) resin
In addition, short shots do not occur with each molded product,
Lines and burrs can be prevented, and the cavity 7_{a ~ H}What
Filling property, especially 7_b, 7_c(7_f, 7_gAt the same time)
A product with improved fillability was obtained. As described above, it can be seen from the above results.
And the curvature runner 5_a, 5_bAdjust the curvature of the
Channel change point 11_b, 11_cControls resin flow inside
By doing, the sprue 2 to the cavity 7_ahLed to
Of the fluidity and / or pressure of the molten resin
Cavity 7_ahEven flow
Is performed and the simultaneous filling property is improved.
_ahThe resin pressure inside becomes uniform. As a result, each molded product
Neither short shot nor weld line or burr
It is possible to supply products whose generation is suppressed. Change
In the present embodiment, the mold is a curvature runner 5._a, 5_b
Only by adjusting the curvature of the
And / or resin pressure uniformity for high accuracy
Can provide high quality molded products with inexpensive molds
Because Further, the runner 3_{a to f}When flowing through
The temperature change of the molten resin and the local temperature change
If it is not visible, it will melt as the temperature of the molten resin changes.
The viscosity characteristics of the resin change, that is, the flow resistance changes.
Me, runner 3_{a to f}Fluidity and / or resin pressure inside
The force cannot be equalized. So, the implementation
In the mold described in the example, the flow path change point 11_b, 11_c
Fluidity in the runner located downstream from and / or
Curvature runner 5 provided for equalizing resin pressure
_a, 5_bCurvature of runner 3_{a to f}Melt flowing inside
By changing the temperature according to the resin temperature difference, the flow path change point 1
1_b, 11_cAdjust the fluidity of the molten resin
Inner 3_{a to f}Fluidity and / or resin pressure
It can be unified. With this configuration, the temperature of the mold is particularly high.
Curvature runner without separate control
5_a, 5_bBy simply adjusting the curvature of the
Lance, that is, good filling balance
Therefore, while providing an inexpensive mold, the cavity
7_ahIs evenly distributed in the cavity 7_ahBut
Simultaneous filling and cavity 7_ahInside
Since the resin pressure is equalized, the cavity 7_ahFrom
Short shots did not occur in each of the obtained molded products.
High-precision, high-quality products that suppress generation of weld lines and burrs
Quality products are supplied. According to the above embodiment, the present invention provides the following
1_b, 11_cAnd channel change point 11_b, 11_cFrom molten resin
Runner 3 on the outflow side_c, 3_eBetween the molten resin
Angle of outflow direction of cold slag well 4_c, 4_eOr
Change point 11_b, 11_cFlow direction of molten resin returning to
As a flow control runner greater than 90 °
Cold slug well 4 at the center_c, 4_eSongs on the side
Rate runner 5_a, 5_bThe cavity 7
_ahFluidity and simultaneous filling, especially 7_b, 7
_c(7_f, 7_g) And simultaneous filling are improved
For this reason, molding important security parts for vehicles that could affect human life
Suitable for producing multi-cavity injection molded products
The present invention provides a simple injection molding method and a mold. It should be noted that an aspect or technical feature of the present invention is that
Change 11_b, 11_cAnd channel change point 11_b, 11_cFrom
Runner 3 on the side where molten resin flows out_c, 3_eBetween
Cold slug well angle of outflow direction of molten resin
4_c, 4_eTo channel change point 11_b, 11_cBack to molten tree
Flow control runner greater than 90 ° to the flow direction of fat
The center of curvature is a cold slag well 4_c, 4_e
Curvature runner 5 on the side _a, 5_bIs that
But this curvature and the runner 3_{a to f}Shape and length
Effect by changing the number of cavities
As a result, other flow control runners such as polygon runners are used.
We do not enumerate the effects of using each one,
Without being limited to those described above, the entire specification and
Described in the drawings or understood by those skilled in the art from the descriptions.
It is recognized based on ideas that can be
It is to be understood that [0027] The multi-cavity injection molding die of the present invention
Flow point, and molten resin flows out of the flow path change point
Between the runner on the side of
Returns from cold slag well to flow change point
Flow control runner greater than 90 ° to the direction of flow
The cavity 7_ahLiquidity and at the same time
Fillability, especially 7_b, 7_c(7_f, 7_gSame as liquidity
The filling time is improved, and as a result,
To prevent weld lines and weld lines or burrs.
In addition, it is possible to provide molded products with good appearance and high strength.
Another advantage is that it can provide molds with low remodeling costs.
In particular, it forms important security parts for vehicles that may affect human life.
High quality and high safety for multi-cavity injection molded products
Injection Molding Method and Injection Mold for Inexpensive Manufacturing
Can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a vertical parting injection mold according to an embodiment of the present invention. FIG. 2 is a view for explaining resin flow in the mold of FIG. 1; FIG. 3 is a plan view of a conventional mold for vertical parting injection molding. FIG. 4 is a view for explaining resin flow in the mold of FIG. 3; FIG. 5 is a view for explaining resin flow in a mold of another conventional example. [Description of Signs] 1 ノ ズ ル Nozzle 2 Sprue 3 a- _f ‥‥‥ Runner 5 _a , 5 _b , 8 _a , 8 _b ‥‥‥ Curvature runner 4 a- _fコ ー ル Cold slug well 6 ‥‥‥ gate _{7 to h} ‥‥‥ cavity _{9 a to c} ‥‥‥ branch point 10, 20 ‥‥‥ mold _{11 a to c} ‥‥‥ flow diversion point

Claims (1)

Claims: 1. A sprue, which is a path for transferring molten resin injected from a resin injection port, and the same molded product which is arranged at an equal distance from the sprue via a plurality of runners. In a multi-cavity molding die of an injection molding machine having a plurality of cavities to be molded and a cold slag well extending beyond a flow path change point of the runner, the inside of the runner communicates with the runner. In order to make the fluidity and / or resin pressure of the molten resin in each of the cavities uniform, the molten resin is provided between the flow path change point and the runner on the side where the molten resin flows out from the flow path change point. A flow control runner whose flow direction angle is larger than 90 ° with respect to the flow direction of the molten resin returning from the cold slag well to the flow path change point.