JPH0729344B2 - Lubrication structure for positioning part of injection mold - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a lubricating structure for a positioning portion of an injection molding die used for injection molding of plastic or the like in a horizontal injection molding machine, and particularly to prevent misalignment. The present invention relates to a lubrication structure for a positioning portion of an injection molding die, which is intended to prevent wear of the positioning portion for use and rust.

[Conventional technology]

For relatively large injection molds for injection molding of large plastic molded parts such as automobile door panels, instrument panels, etc., both the fixed mold and the movable mold of the injection mold have their respective matching parts. By forming a tapered concave and convex, a tapered positioning part is provided, and this positioning part prevents misalignment of both molds when the movable mold is abutted against the fixed mold, or for molding. The injection mold is prevented from being deformed by the injection pressure of the resin.

By the way, the fixed mold and the movable mold of the injection molding die are generally manufactured by machining this from cast steel, and in order to match the cores of both molds in the final process of the production, the positioning part is ground. Adjustments are made by matching the actual products while finishing with the above.

By the way, since both of these types are large and heavy, this centering work is extremely inefficient.

In order to solve this problem, conventionally, as shown in FIG. 4, a positioning plate 72 having a high hardness is attached to a fixed mold 71 of a pair of molds forming the injection molding mold 70. The 72 is finished and the centering adjustment is performed.

As such an injection mold, for example, Japanese Patent Laid-Open No. 58-10103
There is an injection mold as shown as a conventional example in Japanese Patent Publication No.

[Problems to be solved by the invention]

However, in the conventional injection molding die 70, the positioning plate 72 shown in FIG.
73 has been heat treated and the surface has become harder,
In the case of horizontal molding in which the movable mold 74 is driven in the horizontal direction as shown in the figure, the positioning portion 74 of the movable mold 74 is worn during mold clamping due to the bending of the movable mold 74 due to its own weight.

Further, in order to speed up the curing of the resin molded product, that is, in order to improve the productivity, the injection mold 70 is forcibly cooled. However, due to the cooling, the temperature between the temperature of the injection mold 70 and the outside temperature is increased. A temperature difference occurs, and due to this temperature difference, the positioning portion 73 of the positioning plate 72 of the fixed mold 71 that constitutes the injection molding mold 70, and
Moisture may condense on the positioning portion 75 of the movable mold 74, and rust may occur there.

Due to the rust, the positioning portion 73 of the positioning plate 72 of the fixed die 71 and the positioning portion 74 of the movable die 73 are quickly worn.

Further, the positioning portion 75 of the movable die 74 is worn due to the above-described bending, and the positioning portions 73 and 75 of the die 71 and 74 due to rusting.
A gap was generated between the positioning portions 73 and 75 due to wear of the.

If this gap is left as it is, misalignment will occur and molding defects such as burrs and defective wall thickness of the injection molded product will occur. In particular, in the fixed mold 71 of both molds, as shown in FIG. In addition, there was a problem that a crack M was generated.

Therefore, there has been a problem that the frequency of mold modification and mold replacement of the fixed mold 71 is high among the two molds, resulting in a decrease in productivity.

Conventionally, the occurrence of the crack M has been regarded as a fatigue failure of the injection molding die 70, and the strength of the mold has been dealt with, but there is a problem that the weight of the injection molding die 70 increases.
It was not an effective measure.

[Means for solving problems]

Therefore, according to the present invention, a fixed die is arranged so as to face a movable die that is moved back and forth in the horizontal direction, and the center axis of each die is centered on the surfaces of the movable die and the fixed die that face each other. In the lubricating structure for the positioning portion of the injection mold in which the tapered positioning portion is formed, at least one of the positioning portions of the mold is provided with a recess in the positioning portion above the central axis, and the recess is formed in the recess. It is characterized by being filled with a solid lubricant.

[Action]

According to such a configuration of the present invention, sliding at each positioning portion occurs with opening and closing of the mold, the sliding surface is formed so that the recess is opened, and the solid lubricant is filled. , The solid lubricant is spread on the sliding surface of the positioning portion to form a lubricant film. In this way, the lubricant coating is
Since it is formed by being stretched by the sliding of the positioning portion, unlike liquid ones, it does not flow down into the cavity and there is no need for such control. The lubricant film reduces the frictional resistance of the positioning portion and prevents rusting.

〔Example〕

Next, the lubricating structure for the positioning portion of the injection mold according to the first and third embodiments of the present invention will be described with reference to the drawings.

(First Embodiment) First, a lubrication structure for a positioning portion of an injection mold according to the first embodiment will be described with reference to FIGS. 1 and 2.

1 is a sectional view of an injection molding die showing a lubricating structure for a positioning portion of an injection molding die according to a first embodiment of the present invention, and FIG. 2 is an enlarged sectional view of a II portion of the injection molding die of FIG. Show.

In FIG. 1, reference numeral 1 is a resin injection molding die for molding automobile parts, and the injection molding die 1 moves back and forth in a horizontal direction with respect to a fixed die 2 and the fixed die 2 as shown in the drawing. It is configured to perform horizontal molding with the movable mold 3.

The former fixed mold 2 is made of cast steel, and its front surface (right surface in the figure)
Is processed to match the shape of automobile parts that are injection-molded products, and recesses 2a and 2b that form cavities A and B are formed.
In addition, the spool 4 is sorbed in order to inject the molding resin into the cavities A and B.

On the other hand, the latter movable die 3 is processed into a shape in which the concavo-convex shape is reversed from that of the fixed die 2, and the cavity A is formed between the convex portions 3a and 3b and the concave portions 2a and 2b of the fixed die 2. And B are formed.

The movable mold 3 is detachably fixed to a base mold 5 which is moved by a ram (not shown) of the injection molding device.

Reference numeral 6 denotes an extruding rod for pushing apart an injection-molded product (not shown) attached to the surface of the movable mold 3 after the injection molding, and sliding on a sliding hole 3c formed through the movable mold 3. It is housed movably, and after injection molding, its tip projects from the movable mold 3 to push an injection-molded product (not shown) away from the movable mold 3.

Reference numerals 21 and 22 are fixed-side positioning plates, reference numerals 31 and 32 are movable-side positioning plates, and the fixed-side positioning plates 21 and 22 and the movable-side positioning plate 3 are shown.
Reference numerals 1 and 32 are detachably fixed to the cotter portion 23 of the fixed die 2 and the cotter portion 33 of the movable die 3 by screw members (not shown).

The positioning portions 21a, 22a of the fixed-side positioning plates 21, 22 and the positioning portions 31a, 32a of the movable-side positioning plates 31, 32 are the mold matching portions of the two molds 2, 3, that is, the left surface in the figure of the fixed mold 2. Also, two portions are formed on the right surface of the movable die 3 in the figure, respectively.

The two positioning parts 21a and 22a of the fixed mold 2 are formed in a tapered convex shape, and the two positioning parts of the movable mold 3 are arranged.
31a and 32a have a tapered concave shape.

The fixed side positioning plates 21 and 22 and the movable side positioning plates 31 and 32 are formed of tool steel or the like having a hardness higher than that of the fixed mold 2 and the movable mold 3 made of cast steel.

Then, the positioning portions 21a and 3 on the upper side in FIG.
In 1a, as shown in detail in FIG.
And 31b are drilled.

The upper positioning portions 22a and 32a in FIG.
Also, the depressions 21b and 31b are formed in the same manner as the upper positioning portions 21a and 31a.

The recesses 21b, 22b and 31b, 3 provided in the fixed side positioning plates 21, 22 and the movable side positioning plates 31, 32, respectively.
A graphite-based solid lubricant G is embedded in 2b.

With this graphite-based solid lubricant G, the fixed side positioning plates 21, 22 and the movable side positioning plates 31, 32
A good lubricant film is formed on the positioning portions 21a, 22a and 31a, 32a.

Next, the operation of this embodiment will be described.

In order to mold a resin molded product with the injection molding die having the positioning portion lubrication structure configured as described above, first, the movable die 3 is directed toward the fixed die 2 side, that is, the arrow C in FIG. And move both molds 2 and 3 as shown in FIG.
Match.

By such mold matching, both molds 2 and 3 positioning portions 21
a, 22a and 31a, 32a are in surface contact with each other, and by the surface contact of these positioning portions 21a, 22a and 31a, 32a, the movable mold 3 is aligned with the fixed mold 2 without causing misalignment. It is modeled according to the state.

In this state, the molding resin is injected from the spool 4 into the cavities A and B to mold a resin molded product.

After the molding, the movable die 3 is separated from the fixed die 2, and the pushing rod 6 is projected from the molding surface of the movable die 3 to take out the resin molded product attached to the molding surface.

By the way, when the mold is opened, the recesses 21b, 22b and 31b, 32b are in an open state, but the lubricant filled therein is solid, so that the lubricant is used when the mold is opened. Does not flow out. Further, since the positioning portions 21a, 22a and 31a, 32a relatively slide relatively at the time of mold clamping and mold opening, the recesses 21b, 22b and 3 opened here are formed.
Solid lubricant G contained in 1b and 32b is used for each positioning portion.
The surface of 21a, 22a and 31a, 32a is drawn, that is, spread. As a result, the positioning portions 21a, 22a and 31
Since a good lubricant film of the solid lubricant G contained in the depressions 21b, 22b and 31b, 32b is formed in the a and 32a, the frictional resistance of the positioning portions 21a, 22a and 31a, 32a is small, Wear due to galling is reduced, rust can be prevented by the lubricant film, and further wear is reduced.

In this way, since the wear of the positioning portions 21a, 22a and 31a, 32a is significantly reduced, the positioning portions 21a, 22a and 31a, 32a is less likely to create a gap, and therefore the occurrence of misalignment is also suppressed. Therefore, it is possible to suppress the occurrence of molding defects such as burrs or uneven thickness of the molded product.

In the case of the present embodiment, the graphite-based solid lubricant G is used as the lubricant, and the lubricant film formed by the solid lubricant G is formed of solid particles, so that it is unlikely to be a liquid lubricant. Or the positioning portions 21a, 22a of the fixed-side positioning plates 21, 22 and the positioning portions 31a, 32a of the movable-side positioning plates 31, 32 come into direct contact with each other when a heavy load is applied. There is no.

Further, due to the friction heat at the positioning portions 21a, 22a and 31a, 32a at the time of mold clamping and the heat of the injection resin at the time of molding, the positioning portion 21
Even if the temperature of a, 22a and 31a, 32a rises, the solid lubricant G
Does not lose quality or lose its viscosity.

Therefore, it is suitable for a large-sized injection molding die in which the molding pressure largely acts in the mold deviation direction, that is, the direction of arrow D in FIG. 1, an injection molding die for FRP having a high molding temperature, and the like.

(Second Embodiment) Lastly, a positioning part lubricant structure of an injection molding die according to a third embodiment of the present invention will be described with reference to FIG.

FIG. 3 is a cross-sectional view of the injection molding die showing the positioning part lubricant structure of the injection molding die according to the second embodiment of the present invention.
3, the same reference numerals as those shown in FIGS. 1 and 2 denote the same members as those shown in FIGS. 1 and 2.

In this embodiment, the upper positioning portions 21a and 31a of the fixed mold 2 and the movable mold 3 in FIG.
Are formed on the fixed side positioning plate 21 and the movable side positioning plate 31 which are detachably fixed to the cotter portions 23 and 33, and as shown in FIG. 2 showing the first embodiment, this fixed side positioning plate 21 and Movable side positioning plate 31
The depressions 21b and 31b are formed in the
A graphite-based solid lubricant G is embedded as a lubricant.

On the other hand, the lower positioning portions 2d and 3d of the fixed die 2 and the movable die 3 in FIG. 3 are formed directly on the fixed die 2 and the movable die 3, and in the lower positioning portion 2d of the fixed die 2, oil which is a depression is formed. The fixed mold 2 is provided with a groove 2e, a lubricating oil passage 2f is formed below the fixed mold 2, and the lubricating oil passage 2f is opened.
An automatic continuous lubricator 24 is attached to the opening of the.

In the case of the present embodiment, since the solid lubricant G is used as the lubricant in the upper positioning portions 21a and 31a of the fixed mold 2 and the movable mold 3 on which the load is applied, the injection molding mold 1 is large and its positioning is performed. Even if the load applied to the portions 21a and 31a is large, a sufficient lubricating function is exhibited.

Further, since the lubricating oil, which is a liquid lubricant, is used as the lubricant for the lower positioning portion 2d having a smaller load than the upper portion, the cavities A and B above the positioning portion 2d are used.
The lubricating oil does not rise, and it is not necessary to take measures to prevent the lubricating oil from entering the cavities A and B.
The injection molding device is simplified.

〔The invention's effect〕

As described above, according to the present invention, among the positioning portions of the injection molding die including the fixed die and the movable die, the depression is formed in the positioning portion above the horizontal central axis parallel to the moving direction of the movable die. The solid lubricant that is filled in is placed on the positioning part, and a solid and strong lubricant film is formed on the positioning part, so the friction resistance of the positioning part is small, wear due to galling is reduced, and the lubricant film As a result, rust can be prevented from occurring, and wear can be reduced.

In this way, the wear of the positioning portion of the injection molding die is significantly reduced, so that a gap is less likely to occur between the positioning portions of the fixed die and the movable die that are in contact with each other.

Therefore, it is possible to suppress the occurrence of misalignment, and it is possible to suppress the occurrence of molding defects such as burrs or uneven thickness of the molded product.

Also, by suppressing the occurrence of this misalignment, the fixed type or movable type cracks are eliminated, and the frequency of repairing the fixed type or movable type is greatly reduced along with the reduction of the wear of the positioning portion. The excellent effect that the operating rate of the injection molding device can be increased is obtained.

Furthermore, since the occurrence of rust on the positioning part of the injection mold is greatly suppressed, this injection mold can be cooled more strongly than before, and the molding speed can be greatly increased, that is, productivity can be significantly improved. It has an excellent effect.

[Brief description of drawings]

FIG. 1 is a sectional view of an injection molding die showing a positioning part lubricating structure of an injection molding die according to the first embodiment of the present invention, and FIG. 2 is an enlarged sectional view of a II portion of the injection molding die of FIG. is there. FIG. 3 is a sectional view of an injection molding die showing a positioning part lubricating structure of the injection molding die according to the second embodiment of the present invention. FIG. 4 is a cross-sectional view of the injection molding die showing the structure of the positioning portion of the conventional injection molding die. 1 …… Injection mold 2 …… Fixed mold 3 …… Movable mold 21b, 22b, 31b, 32b… Dent G …… Solid lubricant

Claims (1)

[Claims] 1. A fixed die is disposed so as to face a movable die that can be moved back and forth in the horizontal direction, and the center axis of each die is centered on the surfaces of the movable die and the fixed die that face each other. A lubricating structure for a positioning portion of an injection molding die in which a tapered positioning portion is formed, wherein a recess is formed in a positioning portion above the central axis of the positioning portions of at least one mold, and a solid is formed in this depression. A lubricating structure for a positioning portion of an injection molding die, characterized by being filled with a lubricant.