JP4139932B2 - Mold - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mold used for injection molding or transfer molding.
[0002]
[Prior art]
In the mold used in injection molding or transfer molding or the like, the requirement for a mold without generating burrs leakage is a mold opening force due to the mold internal pressure P _1, the clamping force as P _2,
P ₁ ≦ P ₂
It is said that. Here, the mold opening force P ₁ due to the pressure in the mold is obtained by the product of the pressure in the mold generated in the cavity and the projected area of the cavity.
[0003]
However, when the in-mold pressure actually generated in the cavity is measured and applied to the above relational expression, it is not the above expression,
P ₁ << P ₂
Otherwise, the occurrence of burr leakage will not be lost, and this tendency is particularly remarkable in that the filling is completed at the lowest viscosity state of the material such as rubber or thermosetting resin.
[0004]
As a result of investigating this cause, a large amount of clamping force is consumed to eliminate the gap generated in the parting part depending on the processing accuracy related to the parallelism or flatness in the parting part of the molding machine or mold. found.
[0005]
Therefore, the requirement not to generate rubber leakage, etc., P ₁ a mold opening force due to the mold internal _pressure, the clamping force and P _2, P ₁ further the force required to eliminate the gap between the parting portion as P ₃ + P ₃ ≦ P ₂
First, it is necessary to elastically deform the parting part so that the entire parting part comes into contact with no gap depending on the processing accuracy. In this, a great mold clamping force was consumed.
[0006]
[Problems to be solved by the invention]
In view of the above points, the present invention can bring the entire parting part into contact with a relatively small mold clamping force without gaps, thereby preventing both burr leakage from the parting part and reducing the mold clamping force of the mold. It aims at providing the shaping | molding die which can be implement | achieved.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the mold of the present invention is a mold formed by combining a plurality of split molds so as to be freely contactable and separable. The structure that is easy to elastically deform is configured by a recess provided around or part of the parting portion, and the recess is formed on the outer peripheral side or inner peripheral side of the parting portion. It is characterized by being engraved along the part and formed as a recess having a groove shape .
[0008]
When the shape of the parting part is easily elastically deformed by the action of the clamping force as in the mold of the present invention having the above-described configuration, the parting part is in a stage where a relatively small clamping force is applied. Elastically deforms and the entire parting part comes into contact with no gap. Then, in a structure easy thus parting portion elastically deformed and do not modify the material is constituted by a peripheral or recess provided in a portion of the parting unit, said recess, said It is preferable that engraving is made along the parting part on the outer peripheral side or inner peripheral side of the parting part to form a concave part having a groove shape .
[0009]
It is also preferable to set the ratio of the width and height of the parting part small , for the following reason.
[0010]
That is, as shown in FIG. 1, when the height of the parting part 8 is L, the elastic deformation amount of the parting part 8 is ΔL, and the distortion of the parting part 8 is ε, approximately,
ε = △ L / L
And the stress σ due to the clamping force F of the parting portion 8 is relative to the area S of the parting portion 8.
σ = F / S
It is. On the other hand, if the Young's modulus is E,
σ = E · ε
Can be expressed as
F / S = E (△ L / L)
It becomes.
[0011]
The area S of the parting part 8 is designed to have a value that does not cause the plastic parting part 8 to be crushed (not plastically deformed) by the clamping force F at the time of molding. Since the peripheral length of the parting portion 8 is determined, the design value depends on the width t of the parting portion) and cannot be reduced. Accordingly, in order to increase the amount of elastic deformation ΔL of the parting portion 8, the same clamping force F and the same area S of the parting portion 8 are premised. Therefore, the height L of the parting portion 8 is increased. A larger deformation ΔL of the parting portion 8 is obtained.
[0012]
However, if the ratio (t / L) between the width t of the parting part 8 and the height L of the parting part 8 becomes too large, the parting part 8 may be buckled.
t / L = 1-5
It is preferable to set the degree.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
[0014]
First embodiment ...
As shown in FIG. 2 , the mold 1 according to this embodiment has an upper mold 2 and a lower mold 3 as separate molds that come into contact with and separate from each other. The upper mold 2 and the lower mold 3 are connected to the sprue portion 4. , A disc runner portion 5, a gate portion 6, a product portion (also referred to as a cavity) 7, and a parting portion 8, and an annular party provided on the outer surface of the product portion 7 on the upper surface of the lower mold 3. The part 8 is engraved so that the parting portion 8 is elastically deformed as shown in FIG. 3 when a clamping force is applied to a portion on the outer peripheral side of the ring portion 8 . An annular recess (also referred to as an engraved portion) 9 is formed. The concave portion 9 is formed along the parting portion 8 on the outer peripheral side of the parting portion 8, and thus the width t of the parting portion 8 is constant over the entire height thereof. Further, the ratio (t / L) between the width t and the height L of the parting portion 8 is set to be relatively small so that the parting portion 8 is elastically deformed when a clamping force is applied. Specifically, the ratio of the height L to the width t (t / L) is 1 ≦ t / L ≦ 5 according to the above.
Is set to
[0015]
Therefore, according to this mold 1, the parting portion 8 is elastically deformed relatively easily at a stage where a relatively small clamping force is applied, and the parting portion 8 contacts the entire circumference without any gap. In addition, it is possible to prevent burrs from leaking from the parting portion 8 and to reduce the size of the mold clamping force.
[0016]
FIG. 2 shows a state in which the upper side 2 comes into contact with the parting portion 8 of the lower mold 3 due to an error in parallelism between the upper and lower molds 2 and 3, and further clamping force is obtained from this state. As shown in FIG. 3 , the parting portion 8 is elastically deformed, and the upper and lower molds 2 and 3 are completely brought into close contact with each other. Moreover, if the recessed part 9 has a freedom degree in a product shape, even if it provides this inside the parting part 8, the same effect is acquired.
[0017]
Second embodiment ...
As shown in FIG. 4 , the mold 1 according to this embodiment has an upper mold 2 and a lower mold 3 as separate molds that come in contact with and away from each other. The upper mold 2 and the lower mold 3 are connected to the sprue portion 4. , A disc runner portion 5, a gate portion 6, a product portion (also referred to as a cavity) 7, and a parting portion 8, and an annular party provided on the outer surface of the product portion 7 on the upper surface of the lower mold 3. An engraved portion is formed on the outer peripheral surface of the ring portion 8 so that the parting portion 8 is elastically deformed as shown in FIG. 9) is also formed. The concave portion 9 has an annular inclined surface 10 having a reverse taper shape on the inner surface thereof and an annular arc surface 11 having a circular cross section on the lower side thereof. It is formed so as to be gradually reduced from the middle in the height direction to the lower side.
[0018]
Therefore, according to this mold 1, the parting portion 8 is elastically deformed relatively easily at a stage where a relatively small clamping force is applied, and the parting portion 8 contacts the entire circumference without any gap. In addition, it is possible to prevent burrs from leaking from the parting portion 8 and to reduce the size of the mold clamping force. Further, when the concave portion 9 is provided on the side surface of the parting portion 8 as in the present embodiment, the parting portion 8 is elastically deformed so as to fall down when pressurized, so that a larger deformation than usual can be generated.
[0019]
FIG. 4 shows a state in which the upper side 2 comes into contact with the parting portion 8 of the lower mold 3 due to an error in parallelism between the upper and lower molds 2 and 3, and further clamping force is obtained from this state. As shown in FIG. 5 , the parting portion 8 is elastically deformed and the upper and lower molds 2 and 3 are completely brought into close contact with each other. Moreover, if the recessed part 9 has a freedom degree in a product shape, even if it provides this inside the parting part 8, the same effect is acquired.
[0020]
【The invention's effect】
The present invention has the following effects.
[0021]
That is, in the mold of the present invention having the above-described configuration, the entire parting portion can be brought into contact with no gap with a relatively small clamping force, thereby preventing burr leakage from the parting portion and the mold of the mold. Both reductions in tightening force can be realized. Therefore, molding without burr leakage or the like is possible, and the same molded product can be molded with a smaller clamping force.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of elastic deformation of a parting portion according to an embodiment of the present invention. FIG. 2A is a cross-sectional view of a mold according to a first example of the present invention, and FIG. (A) is a cross-sectional view showing the pressed state of the mold, (B) is an enlarged view of the main part of FIG. (A). (A) is the present invention. Sectional drawing of the shaping | molding die concerning 2nd Example of this, (B) is a principal part enlarged view of the same figure (A). FIG. 5 (A) is sectional drawing which shows the pressurization state of the same shaping | molding die, (B) Is an enlarged view of the main part of Fig. (A) [Explanation of symbols]
1 Mold 2 Upper mold (split mold)
3 Lower mold (split type)
4 sprue part 5 disc runner part 6 gate part 7 product part 8 parting part 9 concave part 10 inclined surface 11 arc surface

Claims (1)

In a mold (1) formed by combining a plurality of split molds (2) and (3) so as to be able to contact and separate,
The parting part (8) of the split molds (2) and (3) has a structure that is easily elastically deformed when a clamping force is applied ,
The elastically deformable structure is constituted by a recess (9) provided around or part of the parting part (8),
The said recessed part (9) is engraved along the said parting part (8) in the outer peripheral side or inner peripheral side of the said parting part (8), and is formed as a recessed part which exhibits groove shape. Characteristic mold.

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