JP2004188842A - Mold clamping device for injection compression molding and injection compression molding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To mold a molded product having a uniform wall thickness by correcting the inclination of a movable mold being a problem peculiar to injection compression molding wherein a raw material resin is injected in a mold cavity so as to be biased to one region of the cavity. <P>SOLUTION: In a mold clamping device for injection compression molding wherein the raw material resin 6 is injected in the mold cavity 5 so as to be biased to one region of the cavity to be compressed, a compression force adjusting means 12, which counters the compression force of a movable platen 2 to a fixed platen 1, is provided between the fixed platen 1 and the movable platen 2 in the direction of the part of the cavity 5, where no raw material resin 6 is present, opposed to the raw material resin 6 injected so as to be biased to one region of the cavity 5. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an injection compression molding method in which a raw material resin is injected into one side of a mold cavity.
[0002]
[Prior art]
A conventional device for counteracting a mold clamping force with a spring is an injection molding mold including a fixed mold and a movable mold for injecting and molding a molten thermoplastic resin material into a mold. At least one spring member is provided, one end of which is fixed to at least one of the pair of dies, and the other end of which is disposed so as to be able to abut against the opposing dies during mold clamping. There is an injection compression molding die that absorbs the molding machine die clamping force by the biasing force of the spring member and reduces the force that presses the die cavity. (For example, see Patent Document 1)
[0003]
[Patent Document 1]
Japanese Patent Publication No. 7-33034 (Pages 1-5, Fig. 1-2)
[0004]
In Patent Literature 1, since a spring is provided in a mold, the spring must be incorporated in each mold, which increases the equipment cost and accommodates the spring in a mold with a limited installation location. It is extremely difficult. Further, Patent Document 1 is configured such that a spring force is uniformly applied to the entire mold cavity due to the problem.
[0005]
[Problems to be solved by the invention]
The present invention corrects the inclination of a movable mold, which is a problem inherent in injection compression molding in which a raw material resin is injected into one side of a mold cavity, and molds a molded product having a uniform thickness. With the goal.
[0006]
[Means for Solving the Problems]
Therefore, the present invention is directed to an injection compression molding mold clamping apparatus in which a raw material resin is injected into one side of a cavity in a mold cavity and compresses the raw material resin. Compressive force adjusting means for opposing the compressive force of the movable plate to the fixed plate is provided between the fixed plate and the movable plate in the direction of the cavity where the raw material resin does not exist.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a front view of a partial cross section of a mold clamping device embodying the present invention.
[0008]
The mold clamping device includes a fixed platen 1 and a movable platen 2. A fixed die 3 is attached to the fixed platen 1, and a movable die 4 is attached to the movable platen 2. The movable platen 2 is provided so as to be separated from, close to, and press-closed to the fixed platen 1 by a mold opening / closing means and a mold clamping means (not shown). FIG. 1 shows a vertical mold clamping device as an example, but may be a horizontal mold clamping device.
[0009]
The fixed die 3 has a concave portion 9, into which the convex portion 10 of the movable die 4 enters and fits with the movement of the movable platen 2 to form the cavity 5. A gate 7 is provided on a side surface of the concave portion 9 of the fixed mold 3, and the gate 7 communicates with an outer side surface 11 of the fixed mold 3. The injection device 8 is in contact with the outer side surface 11, and the raw material resin 6 can flow into the cavity 5 from the injection device 8. Although the example in which the gate 7 is provided on the side surface of the concave portion 9 of the fixed mold 3 is shown, the gate 7 may be provided on the bottom surface of the concave portion 9 of the fixed mold 3. In this case, the sprue extending and communicating from the gate to the outside of the fixed mold is bent into an L-shape and opened to the side of the fixed mold, or extended straight and opened to the bottom of the fixed mold. Then, the injection device 8 may freely pass through the through-hole opened in the fixing plate 1 and abut on the opening on the bottom surface of the fixed mold. Further, when the position of the gate provided on the bottom surface of the fixed mold is deviated from the center, the raw resin is also injected to the cavity so that the present invention is effective. Further, even when the gate provided on the bottom surface of the fixed mold is located at the center of the cavity, when the horizontal mold clamping device is used, the raw resin is biased downward by its own weight, so that the present invention can be applied effectively.
[0010]
The operation steps when performing injection compression molding with this mold clamping device will be described step by step. {Circle around (1)} The movable platen 2 is brought close to the fixed platen 1, and the convex portion 10 of the movable mold 4 enters the concave portion 9 of the fixed mold 3 so that the cavity 5 is formed. (3) The movable platen 2 stops moving when it reaches a position where the volume of the molded article increases by a predetermined ratio. (4) The injection device 8 is brought into contact with the outer side surface 11 of the fixed mold 3, and (5) a predetermined amount of the raw resin 6 measured by the volume of the molded product is injected into the cavity 5. When the raw resin 6 is injected into the cavity 5 by a predetermined amount, {circle around (6)} the movable platen 2 is moved to the fixed platen 1 again, and the raw resin in the cavity 5 is compressed and spread.
[0011]
In the above step (5), the raw resin 6 flows from the end face of the cavity 5, so that the fixed mold 3 and the movable mold 4 are pry open, and the fitting surface between the concave portion 9 and the convex portion 10 slightly Since there is a gap, the movable mold 4 is inclined. Therefore, the depth B of the portion of the cavity 5 where the raw material resin 6 is present near the gate 7 is larger than the depth A of the portion of the cavity 5 where the raw material resin 6 is not opposed to the portion. When the next step (6) is performed in this state, the load against the pressing force concentrates on this portion due to the presence of the raw material resin 6 in the portion of the depth B. On the other hand, since there is no raw material resin 6 in the portion of the depth A, there is no load to the pressing force. Therefore, the inclination of the movable mold 4 is further increased. This phenomenon becomes more pronounced as the viscosity of the raw material resin 6 is higher, that is, as the fluidity of the raw material resin 6 is lower.
[0012]
The compression force adjusting means 12 of the present invention is provided to improve the above phenomenon. The compression force adjusting means 12 is provided between the fixed platen 1 and the movable platen 2 in the direction of the cavity 5 where the raw resin 6 does not exist, facing the raw resin 6 which has been injected to one side of the cavity 5. Or a plurality is provided.
[0013]
The cylinder 13 is a cylindrical member into which the adjustment rod 15 is inserted and retracted at one end, and the other end is fixed to a surface of the fixed plate 1 facing the movable plate 2. The side surface of the tube 13 has a through hole and a female screw for loosely engaging and screwing the locking bolt 14. The adjusting rod 15 has a plurality of horizontal holes through which the locking bolts 14 pass through at equal intervals, and is screwed to the other end face of one end inserted into the cylinder 13 via a nut 16 for fixing the adjusting screw 17. The contact rod 18 is loosely inserted into the movable platen 2 via an eight disc spring 19 so as to be coaxial with the adjusting screw 17, and is attached with a double nut 20.
[0014]
The load and the stroke of the compressive force adjusting means 12 required to balance the inclination of the movable mold 4 need to be changed according to the fluidity of the raw resin 6 and the thickness of the molded product. Therefore, the number of the disc springs 19 and the combination (parallel / series) of the disc springs 19 are appropriately selected based on the types of the raw material resin and the mold. A coil spring can be used in place of the disc spring 19, but the disc spring is preferably used because the degree of freedom in selecting the load and the stroke is large and a relatively large load can be obtained despite being small. .
[0015]
An adjusting method of the compression force adjusting means 12 will be described. After the disc spring 19 is inserted through the contact rod 18 and the contact rod 18 is inserted through the movable platen 2, the double nut 20 is fixed so that the disc spring 19 generates an appropriate initial load. 18 is attached to the movable platen 2. In the initial step (5) or (6), the movable die 4 is parallel to the fixed die 3, and the locking bolt 14 and the adjusting screw 17 are adjusted so that the depth A and the depth B match. The locking bolt 14 is used when the thickness of the mold is changed by exchanging the mold composed of the fixed mold 3 and the movable mold 4 to make a relatively large adjustment stepwise. When the raw material resin and molding conditions are changed in the same mold, fine adjustment is performed only by the adjusting screw 17. After the adjustment is completed, the adjusting screw 17 is fixed to the adjusting rod 15 with the nut 16.
[0016]
【The invention's effect】
Since the present invention is configured as described above, the equipment cost is low, it can be easily installed, and despite the injection compression molding in which the raw material resin is injected into one side of the mold cavity in one of the cavities. A molded product having a uniform thickness can be formed without tilting the movable mold.
[Brief description of the drawings]
FIG. 1 is a front view of a partial cross section of a mold clamping device embodying the present invention.
[Explanation of symbols]
1 ... fixed plate 2 ... movable plate 3 ... fixed die 4 ... movable die 5 ... cavity 6 ... material resin 7 ... gate 8 ... injection device 9 ... … Recess 10… protrusion 11… external side surface 12… compression force adjusting means 13… cylinder 14… locking bolt 15… adjustment rod 16… nut 17… adjustment screw 18… abutment rod 19: Belleville spring 20: Double nut A: Depth B: Depth

Claims (3)

Raw material resin is injected into the mold cavity in one side of the cavity, and in an injection compression molding mold clamping device that compresses the raw material resin,
A compressive force between the fixed platen and the movable platen in the direction of the cavity portion where the raw material resin does not exist, which is opposed to the raw material resin injected in one side of the cavity, against the compressive force of the movable platen against the fixed platen. A mold clamping device for injection compression molding, comprising an adjusting means. 2. The injection compression molding die clamping device according to claim 1, wherein said compression force adjusting means comprises a spring whose opposing force increases in accordance with the amount of compression of the movable platen against the fixed platen. In the injection compression molding method in which the raw material resin is injected into the mold cavity to one side of the cavity, and the raw material resin is compressed,
The inclination of the movable platen is corrected by the compression force adjusting means provided between the fixed platen and the movable platen in the direction of the cavity portion where the raw material resin does not exist, facing the raw resin injected in one side of the cavity. And compressing and spreading the raw resin to a uniform thickness over the entire cavity.

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