JP4160927B2 - Mold for synthetic resin compression molding - Google Patents

Description

  The present invention relates to a synthetic resin compression mold, and more particularly to an improvement of a synthetic resin compression mold in which a floating mold prevents burrs from occurring on the outer periphery of a molded product.

  2. Description of the Related Art A molding apparatus for forming a molding cavity by relatively moving a pair of a first molding die and a second molding die in a straight line direction and compressing the synthetic resin material by contracting the molding cavity is widely known. ing. One type of such a molding apparatus includes: (a) a portion of the first mold that constitutes the outer peripheral portion of the molding cavity is disposed so as to be relatively movable in the straight line direction; Is biased in a direction approaching the second mold, and is brought into contact with the die mating surface (die face) of the second mold when forming the approach, and forms a part of the molding cavity, and the bias A floating mold that is integrally moved with the second mold against the urging force of the means and moved relative to the first mold; and (b) the synthetic resin material is compression molded. In some cases, the floating mold is previously brought into contact with the die-mating surface of the second mold to prevent burrs from occurring on the outer peripheral edge of the molded product. The apparatuses described in Patent Documents 1 and 2 are an example.

JP 61-63422 A Japanese Patent Laid-Open No. 3-106625

  However, even in a compression mold having a floating mold as described above, the floating mold is biased by a spring, compressed air, or the like, so its posture is unstable and tilted due to variations in resin pressure during compression molding. A gap was generated between the second mold and burrs were still generated. In addition, because the floating mold is unstable, it is difficult to align with the second mold, so that the mold can be modified so that it can be in uniform contact over the entire circumference, or repaired when burrs occur. However, it was difficult to obtain sufficient mold-matching surface accuracy, and burrs were easily generated in this respect.

  Note that if the floating mold is made of an elastic material that can be elastically deformed, the occurrence of burrs can be prevented more favorably regardless of the above-mentioned inclination and misalignment, but the floating mold forms part of the molding cavity. Therefore, there is a possibility that molding accuracy may be impaired by elastic deformation.

  The present invention has been made in the background of the above circumstances, and the object of the present invention is to incline the floating mold at the time of compression molding without compromising the molding accuracy, or to match the floating mold and the second molding die. Even if the accuracy is not sufficient, it is to prevent the occurrence of burrs well.

  In order to achieve such an object, the present invention provides (a) a pair of first moldings that form a molding cavity by being relatively approached in a straight line direction, and compress the synthetic resin material by contracting the molding cavity. A first mold and a second mold; and (b) a portion of the first mold that constitutes the outer periphery of the molding cavity is disposed so as to be relatively movable in the straight line direction, and by a biasing means. The urging force of the urging means is biased in a direction approaching the second molding die and is brought into contact with the die-mating surface of the second molding die at the time of approaching to form a part of the molding cavity. And a floating mold that is moved relative to the second mold in the direction of approaching the first mold, and (c) before the synthetic resin material is compression molded Floating type is in front In the synthetic resin compression molding die which is prevented from generating burrs on the outer peripheral edge of the molded product by being brought into contact with the mold mating surface of the second molding die, (d) A mounting groove is provided along the outer peripheral edge of the molding cavity in a portion of the mold mating surface located outside the molding cavity, and the molding surface of the second molding die is located inside the mounting groove. (E) A part of the mounting groove protrudes from the mounting groove in a natural state and is aligned with the second molding die while being connected to an outer peripheral edge to form the molding cavity. The floating mold is brought into contact with the surface and elastically deformed and pushed into the mounting groove when the floating mold is pressed against the second mold according to the biasing force of the biasing means. An elastic seal member is provided to allow the mold-matching surface of the second mold to come into contact with the mold-matching surface of the second mold.

  In such a synthetic resin compression mold, when the floating mold is pressed against the second mold in accordance with the biasing force of the biasing means, the elastic seal member is elastically deformed and pushed into the mounting groove. Compression molding is performed with the floating mold mating surface in contact with the mold molding surface of the second mold, and the presence of an elastic seal member prevents leakage of the synthetic resin material and suppresses the generation of burrs. Is done. In that case, the floating mold tilts due to variations in resin pressure during compression molding, or the mating surface accuracy between the floating mold and the second molding mold is not sufficient. Even when a gap is partially formed between the mold mating surfaces (strictly speaking, the connecting portion between the molding surface of the floating mold and the molding surface of the second molding die), leakage of the synthetic resin material by the elastic seal member This prevents the occurrence of burrs and suppresses the occurrence of burrs.

  In addition, the presence of such an elastic seal member alleviates the accuracy required for mold matching for evenly contacting the mold-matching surface of the floating mold and the mold-matching surface of the second mold. When work becomes easy and burrs are generated due to the settling of the elastic seal member, it is only necessary to replace the elastic seal member, which eliminates troublesome mold repair due to overlaying. To do.

  On the other hand, a molding surface that is connected to the outer peripheral edge of the molding surface of the second molding die to form a molding cavity is provided inside the mounting groove, so that the elastic seal member is exposed to the molding cavity and molded. High molding accuracy can be obtained while suppressing the generation of burrs by the elastic seal member without impairing accuracy.

  The present invention is preferably applied to a vertical molding apparatus in which a pair of first molding die and second molding die are relatively moved in a vertical direction that is a straight line direction, but is relatively moved in other directions such as a horizontal direction. It is also possible. The first mold provided with the floating mold is desirably arranged as a lower mold with a fixed position, but the first mold can be moved up and down or arranged as an upper mold.

  Since a burr | flash may generate | occur | produce in the sliding part between the said floating type | mold and a 1st shaping | molding die, it is desirable to comprise a 1st shaping | molding die so that the back surface side of a molded article may be shape | molded. The burr on the outer periphery of the molded product generally needs to be removed because it impairs the aesthetics or prevents the molded product from being attached, but the burr on the back surface does not necessarily need to be removed, and it should not be deburred. It is desirable to determine the shape of a floating type so that burrs are generated. Even when deburring is performed, it can be performed by simple means without considering the beauty after deburring.

  For example, the floating mold or the elastic seal member is provided in an annular shape around the entire circumference of the molding cavity. However, when a burr may be generated due to a part of the outer peripheral edge being hidden in the mounted state of the molded product, A floating mold or an elastic seal member may be provided only on a part of the outer peripheral portion of the molding cavity. For the annular floating mold provided on the entire circumference of the molding cavity, an elastic seal member may be provided only in a part of the circumferential direction.

  As the urging means for urging the floating type, a device that generates a predetermined urging force mechanically, such as a spring such as a compression coil spring or sealed compressed air, is preferably used. Various means can be employed, such as supplying, rotating the feed screw with an electric motor to apply an urging force, or urging with an electromagnetic force.

  In the floating mold, at the time of supplying the synthetic resin material or compression molding, before the synthetic resin material reaches the outer peripheral portion of the molding cavity and leaks from the molding surface, at least the elastic seal member contacts the molding surface of the second molding die. In contact therewith, it is arranged to prevent the leakage. It is desirable that the synthetic resin material reaches the outer peripheral portion in a state where the floating mold is pressed against the second mold by the urging force of the urging means and the elastic seal member is almost completely pushed into the mounting groove.

  The method of supplying the synthetic resin material to the molding cavity is to inject from the injection passage provided in the first molding die or the second molding die, or to form the molding surface of the lower molding die with the molds spaced apart from each other. Various modes are possible, such as supplying the liquid by flowing down.

  The elastic seal member is made of rubber or a synthetic resin material having a predetermined elasticity. For example, a hard urethane resin material is preferably used. The mounting groove in which the elastic seal member is disposed is provided with a cross-sectional area larger than that of the elastic seal member so that the elastic seal member is completely accommodated in the mounting groove by elastic deformation. In order to prevent the synthetic resin material from entering between the elastic seal member and the mounting groove, the positioning groove and the protrusion are arranged so that the elastic seal member is in close contact with the wall surface of the mounting groove on the molding cavity side. It is desirable to perform positioning using positioning means such as engagement, adhesive bonding, or screws.

  The outer peripheral edge (opening edge on the inner peripheral side of the mounting groove) provided on the inner side of the mounting groove of the floating mold is equal to the outer peripheral edge (inner peripheral edge of the mold fitting surface) of the second molding die. In addition, it is desirable that the outer peripheral edge of each of the floating molds is brought into contact with the second molding part in such a way that the outer peripheral edges are substantially in contact with each other. There is no problem even if it is slightly shifted to the outer side or the outer side. When the outer peripheral edge of the molding surface of the second mold is displaced inward from the outer peripheral edge (inner peripheral edge of the elastic seal member) of the floating mold, the molding surface of the second mold and the molding surface of the floating mold While the synthetic resin material may intrude in between, burr may occur, while the outer peripheral edge of the molding surface of the second mold is outside the outer peripheral edge (inner peripheral edge of the elastic seal member) of the floating mold If they deviate, the elastic seal member may be exposed to the molding cavity and the molding accuracy may be impaired, but both may be within the required accuracy range.

  The molding surface provided on the inner side of the mounting groove of the floating mold is provided, for example, on an extension line of the molding surface outside the mounting groove, and when the molding surface is provided at right angles to the straight line direction, It is provided at the same height as the mold mating surface, but the mold mating surface of the floating mold is brought into contact with the mold mating surface of the second molding die so that the outer peripheral edge of the molding surface is the molding surface of the second molding die. What is necessary is just to come in contact with the outer periphery.

  The present invention is a technique for preventing burrs from occurring on the outer peripheral edge of a molded product. However, in the case of a molding die for compression molding an annular molded product, the burrs are formed on the inner peripheral edge of the annular molded product. In order to prevent the occurrence of the floating mold, a floating mold is disposed in a portion of the first mold that constitutes the inner peripheral portion of the molding cavity so as to be relatively movable in the straight line direction. It is also possible to provide an elastic seal member with a mounting groove.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view showing a synthetic resin compression molding die (hereinafter simply referred to as a molding die) 10 according to an embodiment of the present invention. The upper die 14 is disposed above the die 12 and is reciprocated in a vertical direction that is a straight line direction. The upper die 14 is moved downward to approach the lower die 12, thereby 3. As shown in FIG. 4, the synthetic resin material 16 is compression-molded up and down, and the target molded product 18 is obtained. The lower mold 12 is provided with a molding surface 20 corresponding to the back surface shape of the molded product 18, while the upper mold 14 is provided with a molding surface 22 corresponding to the surface shape of the molded product 18, A molding cavity 24 is formed between the molding surfaces 20, 22, etc., and the molding cavity 24 is contracted in the vertical direction as the upper mold 14 is lowered, whereby the synthetic resin material 16 is compression molded. . The lower mold 12 corresponds to a first mold, and the upper mold 14 corresponds to a second mold.

  The outer peripheral portion of the molding surface 20 of the lower mold 12, that is, the portion constituting the outer peripheral portion of the molding cavity 24, is provided with a fitting groove 26 over the entire circumference, and has a shape corresponding to the outer peripheral shape of the molding cavity 24. An annular floating mold 28 is fitted so as to be relatively movable in the vertical direction. The floating mold 28 is biased substantially uniformly by a plurality of compression coil springs 30 functioning as biasing means, that is, in a direction approaching the upper mold 14, and protrudes from the lower mold 12 by a fixed dimension by a stopper (not shown). When the upper mold 14 is lowered during molding, the outer peripheral mold mating surface 32 is brought into contact with the mold mating surface 34 of the upper mold 14, thereby causing the inner peripheral molding surface 36 to As shown in FIG. 3, a part of the molding cavity 24 is formed. In this state, the synthetic resin material 16 is filled into the molding cavity 24 by, for example, an injection device.

  When the upper die 14 is further lowered in this state, the floating die 28 moves relative to the lower die 12 integrally with the upper die 14 against the urging force of the compression coil spring 30. As shown in FIG. 4, the molding surface 36 is pushed into the fitting groove 26 so as to be substantially flush with the molding surface 20 of the lower mold 12, whereby the molding cavity 24 and the target molded product 18 are It becomes the same shape. In FIG. 4, the floating mold 28 is brought into contact with the bottom surface of the fitting groove 26 in this state, but a gap may remain between them. Further, the upper surface of the lower mold 12 outside the floating mold 28 is substantially coincident with the mold mating surface 34 of the upper mold 14, but there may be a predetermined gap between them.

  In this way, the synthetic resin material 16 is filled into the molding cavity 24 by an injection device or the like in a state where the floating die 28 is brought into contact with the die mating surface 34 of the upper die 14 by the compression coil spring 30. The synthetic resin material 16 leaks from between the floating mold 28 and the mating surfaces 32 and 34 of the upper mold 14 when the synthetic resin material 16 is filled or when the upper mold 14 is subsequently lowered. Generation of burrs on the outer peripheral edge of the molded product 18 is suppressed.

  It should be noted that a synthetic resin is provided on the sliding portion between the floating mold 28 and the lower mold 12, specifically, the sliding portion A (see FIG. 4) between the inner peripheral side wall surface of the fitting groove 26 and the floating mold 28. There is a possibility that the material 16 enters and burrs may occur, but since it is on the back surface side of the molded product 18, it does not impair the aesthetics or obstruct the mounting of the molded product 18 and can be left as it is. Even when deburring is performed, it can be performed by simple means without considering the aesthetic appearance after deburring. The inner peripheral shape of the floating mold 28 is determined so that the sliding portion A is located at a position where burrs can be generated.

  On the other hand, in this embodiment, an annular mounting groove 40 is provided on the die mating surface 32 of the floating mold 28 along the outer peripheral edge of the molding cavity 24, and an annular elastic seal member 42 made of a hard urethane resin material is mounted. Has been. FIG. 2 is an enlarged view of a portion where the elastic seal member 42 is mounted. The upper end portion of the elastic seal member 42 protrudes upward from the mounting groove 40 in a natural state before molding, When the floating mold 28 is pressed against the upper mold 14 according to the urging force of the compression coil spring 30 as the upper mold 14 is lowered, the elastic seal member 42 is brought into contact with the mold mating surface 34 of the mold 14. As indicated by the alternate long and short dash line, it is elastically deformed and is completely pushed into the annular groove 40 to allow the die mating surface 32 of the floating die 28 to abut against the die mating surface 34 of the upper die 14. That is, the mounting groove 40 has a cross-sectional area larger than that of the elastic seal member 42 so that the elastic seal member 42 is completely accommodated in the mounting groove 40 by elastic deformation. It is. In that case, in order to prevent the synthetic resin material 16 from entering between the elastic seal member 42 and the mounting groove 40, the elastic seal member 42 is provided on the wall surface of the mounting groove 40 on the molding cavity 24 side (right side in FIG. 2). Are positioned by engaging the positioning groove 44 and the projection 46 so that they are in close contact with each other.

  Further, the inner peripheral edge position of the elastic seal member 42 substantially coincides with the inner peripheral edge position of the die mating surface 34 of the upper mold 14 and is provided substantially horizontally on the inner side thereof, that is, on the inner peripheral side of the mounting groove 40. A molding surface 36a is provided at substantially the same height as the mold mating surface 32, and the mold mating surface 32 of the floating mold 28 is brought into contact with the mold mating surface 34 of the upper die 14, so that the outer peripheral portion of the molding surface 36a is formed. A molding cavity 24 is formed by being connected to the outer peripheral portion of the molding surface 22 of the upper mold 14 so as to intersect at a substantially right angle.

  According to the molding die 10 of this embodiment, when the floating die 28 is pressed against the upper die 14 according to the urging force of the compression coil spring 30, the elastic seal member 42 is elastically deformed and the inside of the mounting groove 40. The compression molding is performed in a state where the mold mating surface 32 of the floating mold 28 is brought into contact with the mold mating surface 34 of the upper mold 14 by being pushed into, but the synthetic resin material 16 is formed by the presence of the elastic seal member 42. The occurrence of burrs due to leakage from the molding cavity 24 to the outside is further effectively suppressed. In that case, the floating mold 28 may be inclined due to variations in resin pressure during compression molding, or the mating surface accuracy of the floating mold 28 and the upper mold 14 may not be sufficient. Even when a gap is partially formed between the mold mating surface 34 of the upper mold 14, strictly speaking, between the outer peripheral edge of the molding surface 36 a of the floating mold 28 and the outer peripheral edge of the molding surface 22 of the upper mold 14, The elastic sealing member 42 prevents the synthetic resin material 16 from leaking out and suppresses the generation of burrs.

  In addition, the presence of such an elastic seal member 42 reduces the accuracy required for matching the floating mold 28 and the upper mold 14, thereby facilitating mold repair work for uniform contact, When burrs are generated due to the settling of the elastic seal member 42, it is only necessary to replace the elastic seal member 42, so that the repair work of the mold due to troublesome build-up is eliminated.

  On the other hand, a molding surface 36 a is provided on the inner peripheral side of the mounting groove 40, and the molding surface 32 of the floating die 28 is brought into contact with the molding surface 34 of the upper die 14, thereby forming the molding surface of the upper die 14. Since the molding cavity 24 is formed by being connected to the outer periphery of the elastic member 22, the elastic sealing member 42 is not exposed to the molding cavity 24 and the molding accuracy is not impaired, and the elastic sealing member 42 generates burrs. High molding accuracy can be obtained while suppressing.

  As mentioned above, although the Example of this invention was described in detail based on drawing, this is an embodiment to the last, and this invention implements in the aspect which added various change and improvement based on the knowledge of those skilled in the art. Can do.

It is sectional drawing which shows the synthetic resin compression mold which is one Example of this invention. It is sectional drawing which expands and shows the part by which the elastic seal member was arrange | positioned among the floating mold | types of the synthetic resin compression mold of FIG. It is sectional drawing which shows the state by which the floating type | mold arrange | positioned by the synthetic resin compression molding metal mold | die of FIG. 1 was made to contact | abut with the upper mold | type by the urging | biasing force of a compression coil spring. FIG. 4 is a cross-sectional view showing a state where the upper mold is further lowered from the state of FIG. 3 and the synthetic resin material is compression molded.

Explanation of symbols

  10: Mold for synthetic resin compression molding 12: Lower mold (first molding mold) 14: Upper mold (second molding mold) 16: Synthetic resin material 18: Molded product 22: Molding surface of upper mold 24: Molding cavity 28 : Floating mold 30: Compression coil spring (biasing means) 32: Floating mold mating surface 34: Upper mold mating surface 36, 36a: Floating mold molding surface 40: Mounting groove 42: Elastic seal member

Claims (1)

A pair of first and second molds for forming a molding cavity by being relatively approached in a straight line direction, and compressing and molding the synthetic resin material by contracting the molding cavity;
A portion of the first mold that constitutes the outer peripheral portion of the molding cavity is disposed so as to be relatively movable in the straight line direction, and is biased by the biasing means in a direction approaching the second mold. A part of the molding cavity that is brought into contact with the die-mating surface of the second mold when approaching, and integrally with the second mold against the biasing force of the biasing means. A floating mold that is relatively moved in a direction approaching the first mold;
And the floating mold is brought into contact with the die-mating surface of the second mold before the synthetic resin material is compression-molded, thereby preventing burrs from occurring on the outer peripheral edge of the molded product. In the mold for synthetic resin compression molding,
The floating mold is provided with a mounting groove along the outer peripheral edge of the molding cavity at a portion of the mold mating surface located outside the molding cavity, and the second molding is formed inside the mounting groove. While provided with a molding surface connected to the outer periphery of the molding surface of the mold to form the molding cavity,
In the natural state, a part of the mounting groove protrudes from the mounting groove and is brought into contact with the die-mating surface of the second mold, and the floating mold is in contact with the second mold according to the biasing force of the biasing means. An elastic seal member is provided that allows the mold-mating surface of the floating mold to come into contact with the mold-mating surface of the second mold by being elastically deformed and pressed into the mounting groove when pressed against the mold. A mold for compression molding of synthetic resin, characterized by

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