JP2963205B2 - Injection mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal mold for injection molding, and more particularly to a metal powder which is required to have a centering accuracy between a fixed mold and a movable mold, and is generated by contact between molds during molding. The present invention relates to a mold which can be suitably used for molding a molded article which is hardly mixed with a foreign substance such as an optical disk and a lens.

[0002]

2. Description of the Related Art Conventionally, as means for centering a fixed mold and a movable mold, a means using a guide pin and a guide bush, a means using a taper pin and a taper pin bush, or a ring cotter is used. Things are known.

[0003]

However, in the conventional means for centering the fixed mold and the movable mold, for example, in the case of using a guide pin and a guide bush, the fitting thereof is directly performed. The clearance between the outer diameter of the guide pin and the inner diameter of the guide bush is always required, so that there is a problem that high-precision alignment cannot be performed. Further, in the case of using a taper pin and a taper pin bush, since the concentricity accuracy and the positional accuracy of the two are required, the accumulated error becomes a problem. In general, a taper pin and a taper pin bush have a small fixed area and a small diameter of a tapered portion, so that a contact area for alignment is small, and tangling or abrasion of a tapered surface occurs. There are difficulties. Further, in the case of using a ring cotter, there is a drawback in that the contact surface, that is, the tapered portion is galled or worn.

Accordingly, an object of the present invention is to use a plurality of positioning cotters to secure the alignment accuracy of a mold in a molded state, and particularly, when opening and closing the mold at a high temperature, at the contact surface of the cotter. Provided is a mold for injection molding that has improved galling resistance and abrasion resistance, and can effectively prevent the generation of foreign substances such as metal powder due to the formation of an oxide film when the mold temperature condition is increased. To be.

[0005]

The injection molding die according to the present invention is provided with a ring for positioning the mold cavity portion in each of the movable die and the fixed die, and the movable die is fixed to the movable ring. In the injection molding die for centering by contact with a side ring, the moving side ring and the fixed side ring are made of a material having the same thermal expansion coefficient as a member forming a mold cavity portion, and A plurality of positioning cotters, which have a tapered surface at a required angle in the radial direction of the cavity and are in contact with each other, are disposed at substantially equal angles in the circumferential direction of each ring at the contact portion between the side ring and the fixed side ring. And the centering is performed.

In the above-mentioned injection mold, the positioning cotter comprises a movable cotter and a fixed cotter which are respectively attached to the movable ring and the fixed ring, and is fixed to the movable cotter when the mold is clamped. When the side cotter is brought into contact with the tapered surface, the facing surface of the cavity between the moving side ring and the fixed side ring in the radial direction has a clearance structure in which a gap is maintained.

In the injection molding die according to the present invention, a ring for positioning the mold cavity is provided on each of the movable die and the fixed die, and the movable ring and the fixed ring are connected to each other. In an injection molding die that performs centering by abutting, a taper of a required angle slidable along a direction normal to the center of the cavity at a contact portion between the moving side ring and the fixed side ring. A plurality of positioning cotters which have a surface and are fitted in the cavity while maintaining a gap in the radial direction may be arranged at substantially equal angles in the circumferential direction to perform centering.

In this case, the positioning cotter comprises a movable cotter and a fixed cotter which are respectively attached to the movable ring and the fixed ring. The movable cotter is provided with a fitting recess, and the fixed cotter is provided with a fitting recess. A fitting convex portion is provided, and the fitting concave portion and the fitting convex portion are configured so as to keep a gap in the radial direction of the cavity and abut on a tapered surface at a required angle in the circumferential direction.

Preferably, the positioning cotter is made of a cemented carbide or a ceramic having a small coefficient of thermal expansion.

[0010]

According to the injection molding die of the present invention, the movable die and the fixed die are provided with rings for positioning the mold cavity, respectively. In the injection mold for centering by contact, the moving side ring and the fixed side ring are made of a material having the same thermal expansion coefficient as the member forming the mold cavity portion. A plurality of positioning cotters having a tapered surface at a required angle in the radial direction of the cavity and being in contact with each other at substantially the same angle in the circumferential direction of each ring are provided, so that the positioning cotters are used when clamping the mold. The centering of the ring can be performed with high accuracy by the contact with the tapered surface.

[0011] Further, a contact portion between the moving side ring and the fixed side ring has a tapered surface of a required angle slidable along a normal direction with respect to a center of the cavity, and a radius of the cavity. By positioning a plurality of positioning cotters at substantially equal angles in the circumferential direction while maintaining a gap in the direction, centering of the ring can be performed even when the moving side ring and the fixed side ring have different coefficients of thermal expansion. Can be performed with high accuracy.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an embodiment of an injection mold according to the present invention.

FIGS. 1 and 2 are a plan view and a sectional view of a main part of an embodiment of an injection mold according to the present invention. That is, FIG. 1 is a plan view of a moving side mold 10 for molding a circular product, reference numeral 12 denotes a nest forming a circular cavity in the center of the mold, and 14 denotes a moving side arranged on the outer periphery thereof. Show the ring. On the other hand, as shown in FIG. 2, the fixed mold 20 also includes a nest 22 forming a circular cavity at the center of the mold and a fixed ring 24 arranged on the outer periphery thereof, as shown in FIG. .

The movable side ring 14 is provided with a vertical step 16 having a predetermined width in the circumferential direction, and a similar step 26 is also provided on the fixed side ring 24 so that these steps 16 and 26 are radially connected. It is constituted so that it may face. Also, the plane 18 located outside the step 16 of the moving side ring 14 is similarly in contact with the plane 28 of the fixed side ring 24 of the fixed side mold 20, and a contact surface of this mold in the mold clamping direction. Is configured.

In this embodiment, however, the step 16 of the movable ring 14 and the step 2 of the fixed ring 24 are different.
The movable side cotters 34 having tapered surfaces 30 and 32 of a required angle in the radial direction of the circular cavity in the mold clamping direction at respective positions corresponding to the movable cotters 34.
In addition, a plurality of fixed cotters 36 (six in the illustrated example) are arranged at equal angles in the circumferential direction. In addition, these cotters 3
Reference numerals 4 and 36 denote a moving side ring 14 and a fixed side ring 24.
And are detachably fixed by screws 38 respectively. In this case, the tapered surfaces 30 and 32 of the movable-side cotter 34 and the fixed-side cotter 36 are used when the movable-side ring 14 and the fixed-side ring 24 abut on the contact surfaces 18 and 28 in the mold clamping direction. In contact therewith, the alignment of the movable side ring 14 and the fixed side ring 24 is performed. Accordingly, the inner diameters of the moving side ring 14 and the fixed side ring 24 are concentric, whereby the insert 12 of the moving side mold 10 and the mold plate 40 supporting the same are securely positioned by these inner diameters. The insert 22 of the fixed mold 20 and the mold plate 42 supporting the insert 22 are accurately and concentrically held.

If the temperature condition of the mold is high, materials having the same thermal expansion coefficient are selected for the insert, the mold plate, the moving side and the fixed side ring which form the mold cavity, and The opposing surfaces of the ring 14 and the fixed side ring 24 at the stepped portions 16 and 26 have a clearance structure with a gap therebetween, and furthermore, the moving side cotter 34 and the fixed side cotter 36
By arranging the combination with at least three locations at substantially equal angles in the circumferential direction, deformation of centering due to thermal expansion of the mold can be prevented. Furthermore, in this case, the moving-side cotter 34 and the fixed-side cotter 36 are made of cemented carbide or ceramic to improve the wear resistance, galling resistance, etc. of these components, and to reduce metal powder or the like due to contact. Occurrence can also be reduced.

FIGS. 3 to 6 show another embodiment of the injection mold of the present invention. For convenience of explanation, the same components as those in the embodiment shown in FIGS. 1 and 2 are denoted by the same reference numerals, and detailed description thereof will be omitted. Therefore, FIG. 3 is a plan view of a main part of a movable mold 10 for forming a circular product as in the above-described embodiment.
5 is a plan view of a main part of the fixed mold 20, FIG. 5 is a cross-sectional view of the main part, and FIG. 6 is a cross-sectional view taken along line AA of FIG.

In this embodiment, however, the movable side ring 14 and the fixed side ring 24 abut on substantially the entire planes 18 and 28 of the rings 14 and 24 without providing a step. It constitutes a contact surface in the tightening direction. At a corresponding inner peripheral edge of the movable side ring 14 and the fixed side ring 24, a required angle at which the slidable along the normal direction with respect to the center of the circular cavity in the mold clamping direction. (See FIG. 6), and the movable cotter 48 and the fixed cotter 5 which are fitted substantially perpendicularly to the radial direction of the circular cavity.
A plurality (0 in the illustrated example) of zeros are arranged at equal angles in the circumferential direction. These cotters 48 and 50 are fitted to the moving side ring 14 and the fixed side ring 24. The moving side cotter 48 is provided with a fitting recess 52 and the fixed side cotter 50 is provided with a fitting projection 54. In this case, the fitting convex portion 54 of the fixed-side cotter 50 is provided with a required gap in the radial direction of the circular cavity with respect to the fitting concave portion 52 of the moving-side cotter 48 to prevent deformation due to thermal expansion of the mold. It is configured to absorb (see FIG. 5).

According to the present embodiment thus constructed, the movable ring 14 and the fixed ring 24 are brought into contact with the contact surface 1.
When abutting in the mold clamping direction at 8, 28, the moving side ring 1
Even if the thermal expansion of the fixed side ring 24 is slightly different from that of the fixed side ring 24, these rings can slide in the normal direction with respect to the center of the circular cavity, and furthermore, can be moved on the moving side where the connection at the tapered surface is performed. The indexing by arranging the combination of the cotter 48 and the fixed-side cotter 50 at at least three locations in the circumferential direction at substantially the same angle enables the centering of the movable-side ring 14 and the fixed-side ring 24 to be performed.

Also in this embodiment, the movable cotter 48 and the fixed cotter 50 are made of cemented carbide or ceramic to improve the wear resistance, galling resistance, etc. of these components. Generation of metal powder and the like due to contact can also be reduced.

[0021]

As is apparent from the above-described embodiment, according to the present invention, the moving side ring and the fixed side ring are made of a material having the same coefficient of thermal expansion as the member forming the mold cavity, and By providing a plurality of positioning cotters, which have a tapered surface of a required angle in the radial direction of the cavity and abut on the abutting portions of these rings, at substantially equal angles in the circumferential direction of each ring, a mold is provided. The centering of the ring can be achieved with high accuracy by the abutment of the positioning cotter by the tapered surface when the mold is clamped.

In this case, the positioning cotter comprises a moving cotter and a fixed cotter which are attached to the moving ring and the fixed ring, respectively. When the mold is clamped, the moving cotter and the fixed cotter are tapered. In the case of contact, the radially opposed surface of the cavity between the moving side ring and the fixed side ring has only a relief structure holding a gap, and high precision centering of the ring can be performed easily and at low cost. Can be realized.

Further, a contact portion between the moving side ring and the fixed side ring has a tapered surface at a required angle slidable along a normal direction with respect to the center of the cavity, and has a radius of the cavity. By arranging a plurality of positioning cotters that are fitted in a circumferential direction at substantially equal angles while holding a gap in the direction, by abutment by the tapered surface of each of the positioning cotters during mold clamping, for example, Even when the moving side ring and the fixed side ring have different coefficients of thermal expansion, centering of the ring can be performed with high accuracy.

Further, since the positioning cotter is made of a cemented carbide or a ceramic having a small coefficient of thermal expansion, these materials are about 1/2 to 1/3 of ordinary steel.
By partially using this in the positioning cotter, it is possible to prevent the deformation of the centering due to the difference in thermal expansion at a low cost, and furthermore, to reduce the wear resistance of the contact surface. Properties and galling resistance can be improved, and the generation of metal powder and the like due to contact can be reduced.

The preferred embodiment of the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and various design changes can be made without departing from the spirit of the present invention. It is.

[Brief description of the drawings]

FIG. 1 is a plan view of a main part of a moving mold, showing one embodiment of an injection mold according to the present invention;

FIG. 2 is a sectional view of a main part of an embodiment of an injection mold according to the present invention;

FIG. 3 is a plan view of a main part of a moving mold, showing another embodiment of the injection mold according to the present invention;

FIG. 4 is a plan view of a main part of a fixed mold in another embodiment of the injection mold according to the present invention;

FIG. 5 is a sectional view of a main part of another embodiment of the injection mold according to the present invention;

FIG. 6 is an enlarged sectional view of a main part taken along line AA of FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Moving side metal mold 12, 22 ... Insert 14 ... Moving side ring 16, 26 ... Step part 18, 28 ... Plane 20 ... Fixed side mold 24 ... Fixed side ring 30, 32 ... Tapered surface 34, 48 ... Moving Side cotters 36, 50 ... Fixed side cotters 38 ... Screws 40, 42 ... Mold plates 44, 46 ... Tapered surface 52 ... Fitting concave parts 54 ... Fitting convex parts

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-63-5915 (JP, A) JP-A-62-140812 (JP, A) JP-A-58-101031 (JP, A) JP-A 57- 8135 (JP, A) JP-A-63-74618 (JP, A) JP-A-64-8013 (JP, A) JP-A-63-188119 (JP, U) JP-A-59-5916 (JP, U) 1-83516 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B29C 45/26-45/44 B29C 33/00-33/76

Claims (5)

(57) [Claims] 1. A mold for injection molding, wherein a ring for positioning a mold cavity is provided in each of a movable mold and a fixed mold, and centering is performed by abutting the movable ring and the fixed ring. In the mold, the moving-side ring and the fixed-side ring are made of a material having a coefficient of thermal expansion equal to that of a member forming a mold cavity, and a contact portion between the moving-side ring and the fixed-side ring has a cavity. A plurality of positioning cotters having a tapered surface at a required angle in the radial direction and being in contact with each other at substantially equal angles in the circumferential direction of the respective rings are arranged to perform centering. Mold for molding. 2. The positioning cotter comprises a moving cotter and a fixed cotter which are respectively attached to a moving ring and a fixed ring. When the mold is clamped, the moving cotter and the fixed cotter are tapered. 2. The injection molding die according to claim 1, wherein when the movable ring and the fixed ring are brought into contact with each other, the radially opposed surfaces of the cavities of the movable side ring and the fixed side ring have a relief structure in which a gap is maintained. 3. A mold for injection molding, wherein a ring for positioning the mold cavity portion is provided on each of the movable mold and the fixed mold, and centering is performed by abutting the movable ring and the fixed ring. In the mold, a contact portion between the moving side ring and the fixed side ring has a tapered surface of a required angle slidable along a normal direction to a center of the cavity, and a radial direction of the cavity. A plurality of positioning cotters are provided at substantially equal angles in the circumferential direction to hold and fit a gap between the cotters. 4. The positioning cotter comprises a moving cotter and a fixed cotter which are respectively attached to a moving ring and a fixed ring, wherein the moving cotter has a fitting recess and is fitted to the fixed cotter. 4. A mating projection according to claim 3, wherein a mating convex portion is provided, and the mating concave portion and the mating convex portion keep a gap in a radial direction of the cavity and abut on a taper surface at a required angle in a circumferential direction. Mold for injection molding. 5. The injection mold according to claim 1, wherein the positioning cotter is made of a cemented carbide or a ceramic having a small coefficient of thermal expansion.