PT104229B - METHOD OF INJECTION MOLDING AND INJECTION MOLDING EQUIPMENT - Google Patents

Abstract

TO ELIMINATE, AS MUCH AS POSSIBLE, A DEFORMATION AND IRREGULARITY OF TRANSFER OF MOLD OF A MOLDED PRODUCT AND TO DECREASE A PERIOD OF TIME OF MOLDING. STEAM IS PROVIDED TO A HEATING MEDIA ROUGE 12 OF A FEMALE MOLD PART 6 TO START THE HEATING OF A CAVITY FORMING SURFACE SIDE TO ENHANCE THEIR TEMPERATURE AND CLOSE A MOLD. Then, when the cavity forming surface reaches a predetermined temperature, the temperature rise is suspended and a predetermined amount of resin is dissolved in a cavity. Subse- quently, a compressed gas is injected into a space between a back surface Of the synthetic resin and the cavity forming surface of the male mold part 27 to enable the compressed gas to press the synthetic resin against the cavity formation surface to form the synthetic resin. AT THE SAME TIME THAT THIS PRESSURE APPLICATION IS EFFECTED, THE COOLING WATER IS PROVIDED TO THE HEATING ROUGE 12 TO CURE THE FRONT SURFACE OF THE SYNTHETIC RESIN OF PART 6 OF FEMALE MOLD. When the synthetic resin is hardened to a certain point, the pressure applied is suspended and the compressed gas is withdrawn to the outside of an injection molding apparatus. AFTER THE EVACUATION OF THE COMPRESSED GAS, COOLING AIR IS INJECTED INTO A SPACE BETWEEN THE BACK SYNTHETIC RESIN SURFACE AND THE CAVITY FORMING SURFACE OF THE MALE MOLD PART 27. HOWEVER, WHEN THE SYNTHETIC RESIN IS STRESSED TO A POINT WHERE THE SYNTHETIC RESIN IS SATISFACTURED HARDLY TO BE REMOVED, THE MOLD IS OPEN.

Description

BACKGROUND OF THE INVENTION

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to an injection molding method and injection molding equipment. More specifically, the present invention relates to an injection molding method comprising a step of injecting a compressed gas into a space between a synthetic resin in a cavity and a cavity forming surface and an injection molding equipment using the method. injection molding machine.

2. DESCRIPTION OF RELATED TECHNIQUE

As disclosed, for example, in Japanese Patent Application Publication No. 06-254924, a method has been proposed in which a side cavity forming surface-front surface to form a front surface side of a molded product is heated beforehand. injection of a fused synthetic resin to thereby improve a transfer property.

SUMMARY OF THE INVENTION

The molten synthetic resin, however, moves inside the cavity while cooling, which is problematic as it results in unsatisfactory uniform spreading of the synthetic resin at the end portions and solidification of the synthetic resin. molten during its flow into the cavity, especially if a sheet thickness of the molded product becomes thicker. In addition, the molding of synthetic resin is time consuming as a high frequency induction heating inductor is oscillated while sandwiched between a stationary mold and a movable mold.

In view of the foregoing problems, the present invention is intended to eliminate as much as possible a deformation of the molded product and a mold transfer irregularity and to reduce a molding time.

A first aspect of the present invention relates to an injection molding method for injecting a molten synthetic resin into a cavity formed between a female mold and a male mold, after heating a cavity forming surface side of the female mold, injecting gas compressed in a space between a rear side of the synthetic resin and a cavity forming surface of the male mold, and provide molding by pressing a front surface of the synthetic resin against the cavity forming surface of the female mold, characterized in that it comprises the steps of:

when a plurality of bushings to form a thin wall part or an opening part, or both, in a molded product is provided in a concave part formed on a top surface of the male mold, collecting the injected compressed gas into the cavity in a tank through a space between a bushing and the male mold, so as not to provide excessive compression, greater than necessary, over a part where the synthetic resin can be pressurized against the cavity forming surface of the female mold, while the compressed gas collected in the The tank is provided, through a gap between the other bushing and the male mold, to a part where insufficient compression of the compressed gas is applied.

A second aspect relates to injection molding equipment which is configured to inject a synthetic resin melt into a cavity formed between a female mold and a male mold after heating a cavity forming surface side of the female mold, injecting compressed gas. in a space between a rear surface of the synthetic resin and a cavity forming surface of the male mold and providing molding by pressing a front surface of the synthetic resin against the cavity forming surface of the female mold, characterized in that:

a bottom surface of the cavity is comprised of a bottom surface forming part and the male mold, an upwardly projecting protruding portion so as to penetrate the cavity is formed at least one end surface portion of top of the bottom surface forming part of a joint part between the bottom surface forming part and the male mold so as to be formed into a frame shape along the joint part, and a groove between the projecting portion and the male mold.

A third aspect relates to injection molding equipment according to the second aspect, characterized in that:

the cavity is constituted by a space extending in a horizontal direction and a cylindrical space forming a continuity with this space and extending in a vertical direction and a bottom surface of a cylindrical part of the cavity consisting of a base part of mold serving as the bottom surface forming part, the mold base part to which the male mold is attached, and the male mold; and wherein an upwardly projecting protruding portion into the cavity is formed along a joining portion to be formed in a frame shape at a top surface end portion of the mold base portion at the coupling part with the male mold, and a groove is formed between the projecting part and the male mold.

A fourth aspect relates to injection molding equipment according to the second aspect, characterized in that:

the cavity is comprised of a space extending in a horizontal direction and a cylindrical space forming a continuity with this space and extending in a vertical direction, and a bottom surface of a cylindrical part of the cavity consisting of a base part mold serving as the bottom surface forming part, the mold base part to which the male mold is attached, and the male mold; and wherein an upwardly projecting protruding part to the cavity is formed at each top surface end portion of a joint part between the mold base part and the male mold so as to be formed into a frame shape along the joint portion, and both projecting portions provide a groove in an upper portion when both projecting portions engage with each other.

A fifth aspect relates to injection molding equipment according to the second aspect, characterized in that:

a bushing that penetrates the cavity is engaged with a concave portion formed on a top surface of the male mold to be secured therein;

wherein a bottom surface forming section forming a bottom surface of the cavity with the male mold is formed in an outer circumferential portion of the bushing, and a first protruding part that penetrates the cavity is formed in a top surface end portion. of the bottom surface forming section;

wherein a second protruding part that penetrates into the cavity is formed on a top surface of the male mold to surround the first protruding part on the outside, and wherein a groove is formed between the second protruding part and the first protruding part.

A sixth aspect relates to injection molding equipment according to the second aspect, characterized in that:

a sleeve, which penetrates into the cavity and whose top portion contacts the female mold to form an opening part in a molded product, is engaged with a concave portion formed on a top surface of the male mold to be secured therein;

wherein a bottom surface forming section forming a bottom surface of the cavity with the male mold is formed in an outer circumferential portion of the bushing and a first protruding part that penetrates the cavity is formed in a top surface end portion of the bushing. bottom surface forming section;

wherein a second protruding part that penetrates into the cavity is formed on a top surface of the male mold to surround the first protruding part on the outside, and wherein a groove is formed between the second protruding part and the first protruding part.

A seventh aspect relates to injection molding equipment according to the second aspect, characterized in that:

a bushing serving as the bottom surface forming portion to be engaged with a concave portion formed on a top surface of the male mold to be secured therein;

wherein a first hollow-penetrating protruding part is formed on a top surface end portion of the bushing top surface along a male mold joining portion, and a second hollow-penetrating protruding part is formed on a cavity-forming top portion. circumferential edge of an opening forming the concave portion on the top surface of the male mold, the second projecting portion projecting at a higher height than the first projecting portion; and wherein a groove is formed between the second projecting part and the first projecting part.

According to the present invention, a deformation and mold transfer irregularity of the molded product can be eliminated as much as possible and a molding time can be reduced. Furthermore, with respect to the molded product including a thin wall part, the mold transfer irregularity can be improved in the thin wall part.

BRIEF DESCRIPTION OF DRAWINGS

Fig. 1 is a longitudinal front elevational view of an injection molding apparatus;

Fig. 2 is a plan view of a male mold part;

Fig. 3 is a cross-sectional view of the male mold part of Fig. 2 taken along line A-A;

Fig. 4 is a cross-sectional view of the male mold part of Fig. 2 taken along line A-A in a state in which a synthetic resin is injected;

Fig. 5 is a cross-sectional view of the male mold part of Fig. 2 taken along line A-A in a state of pressure applied to the synthetic resin after the injection process;

Fig. 6 is a longitudinal sectional view of a bottom surface of an outer circumferential portion of a cavity;

Fig. 7 is a longitudinal sectional view illustrating main parts of a female mold part, a first bushing and the male mold part;

Fig. 8 is an enlarged longitudinal sectional view illustrating major portions of the female mold part, first bushing and male mold part for purposes of explaining a molding process;

Fig. 9 is a longitudinal sectional view illustrating main parts of the female mold part, a second bushing and the male mold part;

Fig. 10 is a longitudinal sectional view of the bottom surface of the outer circumferential portion of the cavity;

Fig. 11 is a longitudinal sectional view of the bottom surface of the outer circumferential portion of the cavity;

Fig. 12 is a longitudinal sectional view of the bottom surface of the outer circumferential portion of the cavity;

Fig. 13 is a longitudinal sectional view illustrating main parts of thin wall forming parts of the female mold part and the male mold part;

Fig. 14 is an enlarged longitudinal sectional view illustrating major portions of the thin-wall forming portions of the female mold portion and the male mold portion for purposes of explaining a molding process;

Fig. 15 is a longitudinal sectional view illustrating major portions of the female mold part, first bushing and male mold part;

Fig. 16 is an enlarged longitudinal sectional view illustrating major portions of the female mold part, the second bushing and the male mold part;

Fig. 17 is an enlarged longitudinal sectional view illustrating major portions of the female mold part, the second bushing and the male mold part;

Fig. 18 is a longitudinal sectional view illustrating major parts of the female mold part, the second bushing and the male mold part;

Fig. 19 is a plan view of a bushing;

Fig. 20 is a cross-sectional view of the bushing of Fig. 19 taken along line B-B in a state in which the synthetic resin is injected;

Fig. 21 is a cross-sectional view of the bushing of Fig. 19 taken along line B-B in a state in which compressed gas is injected;

Fig. 22 is a cross-sectional view of the bushing of Fig. 19 taken along line B-B in a pressure-applied state after the injection process;

THE Fig. 23 is a plan view of the bushing; THE Fig. 24 is a cross-sectional view of the bushing of Fig. 23 as the line C-C on one state in which the synthetic resin is injected; THE Fig. 25 is a cross-sectional view of the bushing of Fig. 23 as the line c-c on one state in which compressed gas is injected; THE Fig. 26 is a cross-sectional view of the bushing of Fig. 23 as

the C-C line in a pressure applied state after the injection process;

Fig. 27 is an enlarged partial view of Fig. 26; and

Fig. 28 is a longitudinal plan view of a molded product.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be described below with reference to the drawings. Initially, a total configuration of the injection molding equipment will be described with reference to the

Fig. 1. 1 indicates a fastened side assembly fastened to a fastening plate not shown by screws, including fastened side assembly 1 a first fastened side base plate 2, a second fastened side base plate 3 fastened to the first side base plate 2 secured by screws, a third side base plate 4 secured to the second side plate 3 secured by screws, a female mold part 6 (a fixed mold part) which is disposed in a concave portion of the third side base plate 4 fastened and secured to the third side base plate 4 fastened by screws, a positioning ring 7 which is provided in a position next to the fastening mold holder of the first side base plate 2 fastened and provides for positioning of the first side base plate 2 secured relative to the holding mold holder, an injection nozzle 8 disposed next to the positioning ring 7 and the others.

A pouring channel 9, which permits injection of the melt synthetic resin from a through-shown nozzle nozzle, is formed in a center of the injection nozzle 8, a feed channel 10 is formed in a central portion thereof. lower end and furthermore multiple ports 11 are formed which function as outputs of the feed channel 10. In addition, 12 indicates a path of the heating medium formed in a section near a cavity S of the female mold part 6 to accompany the cavity S, which allows a hot steam, such as a heating medium, or a water as a cooling means flow in the path 12 of the heating means, thereby heating or cooling a cavity forming surface side of the female mold part 6.

indicates a movable side assembly attached to a movable mold holder, not shown, by screws, including movable side assembly 20 a first movable side base plate 21, a second movable side base plate 22 (ejector plate) attached to the first movable side base plate 21 via screws, a third movable side base plate 23 fastened to first movable side base plate 21 through screws to surround second movable side base plate 22, a fourth side base plate 24 the movable side is secured to the third movable side base plate 23 by bolts, a mold base part 26 engaged with a concave portion of the fourth movable base plate 24 to be secured to the fourth movable base plate 24, a mold part 27 quasi-cuboidal tongue engaged in a concave portion of the mold base part 26 so as to be secured to the mold base part 26 and the others.

An upwardly projecting guide bar (not shown) from the third movable side base plate 23 is inserted into a guide hole provided in the third side base plate 4 secured to be guided by the guide hole, thereby allowing moving side assembly 20 to move upwards and downwards.

Then, in Fig. 2, which is a plan view of the square-shaped male mold part 27 (a movable mold part) in a planar view, and in Fig. 3, which is a sectional view of Fig. 2 second line AA is a cavity S which is comprised, for example, of a rectangular space extending in a horizontal direction in a planar view and, for example, a square cylindrical space extending in a vertical direction from an outer circumferential part of the rectangular space serve to mold a molded product having a shape of a box top cover with an open top surface (having a rectangular horizontal surface and four vertical surfaces extending vertically downwards from each side of the horizontal surface ). In this case, a continuous thin-walled U-shape having a predetermined width and a square (wire-like) frame-shaped contour is formed on a rear surface side of the molded product. The four sides of the thin-walled U-part may have the same thickness or may have different thicknesses.

28A and 28B indicate gas injection paths to provide a compressed gas (e.g., a nitrogen gas, air or the like) from a source of compressed gas not shown to cavity S via supply valves. 29A and 29B are gas exhaust channels for evacuating compressed gas within cavity S out of injection molding equipment through exhaust valves.

As illustrated in Fig. 6, a joint part between the mold base part and the male mold part 27 is positioned in the middle of a bottom surface of the outer circumferential part of the cavity S forming the vertical surface of the molded product and the The bottom surface of the outer circumferential portion of the cavity S is defined by the mold base part 26 and the male mold part. The end portions of the top surface of the corresponding portion between the mold base portion 26 and the male mold portion 27 are provided with projecting portions 30, 31, respectively, of the projecting end portions of the top surface. up to the same height to penetrate cavity S and to be formed into a square (wire-shaped) frame shape. An outer side portion of an upper portion of the protruding portion 31 is partially cut away, and thus, when the protruding portions 30, 31 engage with one another, their lower portions come in close contact with one another while their upper portions form a slot 34.

In other words, the protruding part 30 of the mold base part 26 is formed such that each of the side surfaces defining the concave portion for receiving the male mold part 27 of the mold base part 26 extends vertically in the upwardly inclined as it extends outwards, which gives rise to the approximate shape of a right triangle in a longitudinal plane including a vertex angle of about 20 to 45 degrees. In addition, the protruding part 31 of the male mold part 27 is formed such that each side surface of the male mold part 27 comes into contact with each side surface of the mold base part 26 forming the concave extends vertically upwards extending to the same height as the protruding part 30 and subsequently an outer part of the upper part of the protruding part 31 is partially cut out and then the lateral surface of the male mold part is inclined as it extends inwards, which gives rise to the approximate shape of a right triangle in a longitudinal plane including a vertex angle of about 20 to 45 degrees. Thus, the slot 34 having a width which does not allow compressed gas G to enter when the protruding parts 30 and 31 engage with each other (e.g. 0.5 mm or less in width) is formed in the upper part of the protrusions.

indicates a concave part formed on a top surface of the male mold part 27 for the purpose of forming a downwardly projecting rib toward a bottom surface of the molded product and 33 indicates a concave part formed on a top surface of the molded part. male mold part 27 likewise for forming a hollow cylindrical part that projects downwardly toward the bottom surface of the molded product.

Next, in Fig. 7, 35 indicates a first bushing in the form of a thin wall forming part which is engaged with the concave part of the top surface of the male mold part 27, the concave part having a predetermined width and having a continuous contour in the form of a square (wire-shaped) frame type and the first bushing 35 is configured so that an upper part thereof penetrates into the cavity S, a longitudinal plane of the upper part has an isosceles trapezoid shape including an upper base shorter and longer bottom base, a distance between a plane 42 of the top portion formed in a full circumferential portion of the top portion of the first bushing 35 and the female mold portion 6 is shorter than that of the other portions and the contour The continuous shape having the predetermined width as described above contributes to forming the thin-walled square-frame U-shaped part (wire-shaped) in a molded product.

The protruding portions 36, 37 penetrating the cavity S are formed so that the protruding portions 36, 37 protrude from an outer circumferential portion and an inner circumferential portion of the top surface of the first bushing 35 and are formed with a square frame shape (wire form) in plan view and an outer surface and an inner surface of the first bushing 35 extend upwardly lower than the plane 42 of the tops and are inclined as they extend inwardly, which gives rise to a longitudinal plane having the approximate shape of a right triangle including a vertex angle of, for example, 20 to 40 degrees, as well as having tapered parts 38, 39 at their tops. That is, a height of a transverse portion between oblique side portions forming the protruding portions 36, 37 and an oblique side portion of the first bushing 35 having an isosceles trapezoidal longitudinal plane is equal to a height of the bottom surface defining the cavity S, both oblique lateral parts intersect, forming an angle of about 90 degrees, i. e., practically a right angle and top portions of the protruding portions 36, 37 are provided with tapered portions 38, 39, respectively, which have good thermal conductivity.

Next, in Fig. 9, 40 indicates a second bushing in the form of an opening forming part for forming a through hole in a molded product, the second bushing engaged with the concave part of the top surface of the male mold part 27. it is attached thereto having approximately a cuboid shape and including contacting the top end with the female mold part 6 when the mold is tightened. In other words, the second bushing 40 has a larger flat area fastening portion 40A that is engaged with the concave portion of the top surface of the male mold part 27 and a small portion 40B which is provided on the upper part of the upper portion. 40A with a step mounting to form a through hole in a molded product, with a top surface of the small portion 40B in contact with the female mold part 6 and an outer circumferential end portion of the top surface of the second bushing 40, i. e., an outer circumferential end portion of the top surface of the through hole forming part 40B is provided with a shorter width protruding part 41 such that each of the outer surfaces of the second bushing 40 protrudes. extend upward to penetrate cavity S.

In addition, the protruding part 44 is provided on the top surface of the male mold part 27 to form a groove 53 with a small gap between the protruding part 44 and the protruding part 41 and engaging the protruding part 41 from the outside. in a state where the second bushing 40 is engaged with the concave portion of the top surface of the male mold part 27. In this case, the protruding part 41 of the second bushing 40 is the same height as that of the protruding part 44 of the male mold part 27 and a depth of the groove 54 having a width of the opening formed therebetween is a width which does not allow entry of gas G is compressed and is slightly less than a depth of cavity S. Then, the protruding part 41 of the second bushing 40 and the protruding part 44 of the male mold part 27 are formed with a square frame shape (wire shape) in a planar view.

In Figs. 1 and 3, indicate multiple exit and entry paths to establish communication between a gap between the first bushing 35 and the male mold portion and a compression tank 47 and 49 indicate an inlet and outlet path 49 to establish communication between a space between the second bushing 40 and the male mold part 27 and the compression tank 47.

Compression reservoir 47 is coupled to the outside of the injection molding equipment via an exhaust passage 50 with an exhaust valve.

With the configuration described above, at an injection molding height, hot steam as a heating means is initially supplied to the heating path 12 of the female mold part 6 to heat the cavity-forming surface side of the mold. female mold part 6 and a temperature rise is initiated to a predetermined temperature within a range of 80 to 200 degrees according to a type of synthetic resin to be injected into cavity S, thereby allowing lateral assembly 1 and the movable side assembly 20 are tightened for molding (see Fig. 3). As described above, the temperature rise may be initiated at the same time as the mold is tightened or may be initiated after the mold is tightened, in addition to the case where the mold tightening is effected after the temperature rise has commenced.

When a cavity-forming surface side temperature of the female mold part 6 reaches the predetermined temperature, the temperature rise is stopped by stopping hot steam delivery and the nozzle is inserted into an injection nozzle 8 and the resin The melt is injected into the cavity S between the male mold part 27 and the female mold part 6 from a die 11 through the leakage channel 9. In this case, the synthetic resin J is fused to an amount ranging from 80 wt% or greater to 98 wt% or less, for example about 90 wt%, of a cavity free space S is injected (see Fig. 4).

When molten synthetic resin J is injected at about 90 wt%, compressed gas G of about 10 wt% of cavity S free space is supplied from the compressed gas source to cavity S via the feed valve. and gas injection paths 28A, 28B. Compressed gas G is injected into a space between a back surface of the molten synthetic resin J and the cavity forming surface of the male mold part 27, thereby providing molding by pressing a surface of the molten synthetic resin J against the surface. cavity forming surface of male mold part 27 (see Fig. 5). Accordingly, the occurrence of a surface sinking on a surface of the molded product is suppressed, as well as improving the transfer property, thereby eliminating as much as possible an anomalous appearance.

After injection of compressed gas G, i. e., immediately before or immediately after injection of the compressed G gas, or at the time of injection of the compressed G gas, cooling water is begun to be provided to the heating path 12 of the female mold part 6 to cure the synthetic resin J on the cavity forming surface side of the female mold part 6. Thereafter, the surface of the synthetic resin J is cooled, while molding is provided by exerting pressure by the compressed gas, injection is stopped when the synthetic resin J has cured to a certain extent, for example until a point at which the resin can be shaped and then compressed gas G within cavity S is evacuated out of the injection molding equipment. After the compressed gas has been completely evacuated out of the injection molding equipment, fresh air instead of the compressed gas is introduced into the space between the back surface of the synthetic resin and the cavity forming surface of the mold part 27. through the gas injection paths 28A, 28B. In other words, the back surface of the synthetic resin (the cavity-forming surface side of the male mold part 27) is cooled slightly later than the front surface of the synthetic resin (the cavity-forming surface side of the mold). female mold part 6) at a temperature at or slightly below the cooling temperature of the synthetic resin front surface.

Therefore, when the back surface of the synthetic resin was not cooled, a warping of the molded product could occur due to the difference in shrinkage between the front surface side and the back surface side according to a temperature difference. However, the above cooling process makes it possible to shorten the molding time as well as overcome the problem of shrinkage of the molded product. In addition, the reason why the temperature of the rear side of the synthetic resin is cooled to slightly below the temperature of the front surface of the synthetic resin is to prevent the molded product from being deformed by an ejector pin at the time of demoulding. of the molded product and the reason why the temperature of the rear side of the synthetic resin is lowered to a temperature nearly equal to the temperature of the front surface of the synthetic resin is to further decrease the molding time, provided there is no deformation problem caused through the ejector pin.

After the synthetic resin has cured to a sufficient extent to remove it from cavity S, the injection of cooling air into cavity S and the supply of cooling water to the heating path 12 of the female mold part 6 is interrupted to, subsequently opening the mold, demolding the molded product by the ejector pin and preparing the further production of the molded product again as described above.

In this case, when compressed gas G is injected into a space between the molten synthetic resin J and the cavity forming surface of the male mold part 27 and the front surface of the molten synthetic resin J is pressed against the cavity forming surface. of the female mold part 6 for molding of the synthetic resin, it is necessary to spread the molten synthetic resin J into all corners of cavity S and to make the density of the molten synthetic resin J a uniform density, thereby obtaining thus a good transfer property. Specific embodiments for obtaining the foregoing will be described below.

Initially, and referring to Fig. 6, a molding process on the bottom surface of the outer circumferential portion of cavity S is explained, which is a location in which the fused synthetic resin J is hardly spread with uniform density. That is, the bottom surface of the outer circumferential part of the cavity S is constituted by the male mold part 26 and the female mold part 27 and the corresponding part between the male mold part 26 and the female mold part 27 is positioned. in the middle of cavity S forming the vertical surface of the molded product, so that when a certain amount of compressed gas G is injected into cavity S via gas injection paths 28A, 28B, an interior of cavity S shows a state as 6A and, when more compressed gas G is injected, the molten synthetic resin J is further spread toward the corresponding part between male mold part 26 and female mold part 27, i. e., an end portion of cavity S.

In this case, when the front surface of the molten synthetic resin J is slightly cured while moving, a top end of the synthetic resin contacts the protruding parts 30, 31 of the male mold part 26 and the female mold part 27. (see Fig. 6B), synthetic resin J penetrates a portion of slot 34 having a width that does not allow compressed gas G to enter (for example, a width of 0.5 mm or less) and the front surface slightly Cured synthetic J resin is split to allow softer synthetic resin to exit. Accordingly, the melt synthetic resin J spreads to the corresponding part between the male mold part 26 and the female mold part 27, i.e. e., an end portion of cavity S. In particular, since the softer molten synthetic resin J exits through the entire slot 34, the compressed gas is prevented from circumventing the female or outwardly molded part 6. Injection molding equipment through a gap between the female mold part 27 and the male mold part 26, the front surface of the synthetic resin can be satisfactorily molded by exerting pressure from the front surface of the synthetic resin. against the cavity forming surface of the female mold part 6 due to the compressed gas.

In this case, a thin rib is left in the molded product due to the slot 34; however, this rib does not project outwardly beyond the contour of the molded product, so the molded product will not have a problem related to the function or appearance of the molded product.

Next, it is described with reference to Figs. 7 and 8, a molding process around first bushing 35, wherein the fused synthetic resin J cannot have the uniform density of the fused synthetic resin. Initially, when compressed gas G is injected into cavity S through gas injection paths 28A, 28B so that the front surface of the molten synthetic resin J is pressurized against the cavity forming surface of the female mold part 6 to apply a pressure on the synthetic resin after the injection process, the compressed gas G reaches the side surfaces of the projecting portions 36, 37 of the first bushing 35 to come into contact with them.

In addition, when compressed gas G is injected into cavity S, the compressed gas rises to reach the tapered parts 38, 39 of the protruding parts 36, 37 (see Fig. 8B), it passes over the tapered parts 38, 39 (see Fig. 80) and reaches the base portions of the inclined portions of the protruding portions 36, 37, thereby partially reaching the oblique side portion of the first bushing 35 (see Fig. 8E) or failing to reach it. partially to the oblique side of the first bushing 35 (see Fig. 8D). In this case, the tapered parts 38, 39 store heat from the fused synthetic resin J.

As a result, the synthetic resin J becomes softer according to the heat stored by the tapered parts 38, 39, and therefore compressed gas G passes over the projecting parts 36, 37 to move to a storage basin. defined by the oblique side portions of the protruding portions 36, 37 and the oblique side portion of the first bushing 35. In this way, compressed gas G eventually reaches the entire storage basin area (see Fig. 8F). Accordingly, the compressed gas G having reached the storage basin pressurizes the synthetic resin J so as to push the synthetic resin upwards along the oblique side portion of the first bushing 35 since an angle between the oblique side portions of the portions 36, 37 protruding and the oblique side portion of the first bushing 35 is approximately a right angle and the synthetic resin of a part where the distance between a flat portion 42 of the top part of the first bushing 35 and the female mold part 6 is short (narrow) can be pressurized to uniform density (In Fig. 7, an arrow shows the direction of pressurization) and thus irregularities of mold transfer and deformation can be prevented even when the molded product is endowed with the thin-walled U-part.

In this case, the compressed gas G within cavity S is collected in the compression tank 47 through a small gap between the male mold part 27 and the first bushing 35 so as not to apply excessive pressure to a part in which the synthetic resin J is pressurized against the cavity forming side of the female mold part 6 by the compressed gas G. On the other hand, the compressed gas collected in the compression tank 47 is supplied to the cavity S through the small space and the outlet and inlet path 48 to allow the compressed gas to pressurize an unsatisfactorily pressurized part. Therefore, the compressed gas will not rise along the oblique side of the first bushing 35, but a uniform density across the circumference of the thin-walled U-shaped portion of the molded product can be achieved, thereby allowing the molded product adopts the shape of the mold.

Thereafter, the compressed gas is injected into the cavity S through the gas injection paths 28A, 28B in order to apply pressure to the synthetic resin by pressing the front surface of the synthetic resin against the cavity forming surface of the female mold part 6. which is useful if a through hole is formed in the molded product. This will be described later with reference to Fig. 9.

That is, as illustrated in Fig. 9, the molten synthetic resin J, having been injected into cavity S, passes over the protruding part 44 of the top surface of the male mold part 27 when pressurized with the compressed gas to travel. into groove 54 defined with protruding part 41 and protruding part 44, further reaching groove 53 defined with through-hole forming part 40B and protruding part 41 of second bushing 40.

In this case, the compressed gas G is collected in the compression tank 47 through a small gap between the male mold part 27 and the second bushing 40 and the outlet and inlet path 49 so as not to apply excessive pressure to the part in which the pressure is removed. Synthetic resin J may be pressurized against the cavity forming side of the female mold part 6 by the compressed gas G. On the other hand, the compressed gas collected in the compression tank 47 is supplied to the cavity S through the small space and the outlet and inlet path 48 to be spread over an unsatisfactorily pressurized part.

As described above, a flow of compressed gas G is suspended by using an effect of the compression tank 47 or by allowing the synthetic resin to penetrate the slots 53,

54, thereby, the compressed gas G is flowed to the other parts in order to increase a volume of the compressed gas G within cavity S in order to apply pressure thereon, thereby increasing the density of the synthetic resin. around the through hole (opening portion) of the molded product. Consequently, the pressure around the through-hole (opening part) rises due to pressurization and the temperature of the synthetic resin decreases due to the male mold part 27 whose temperature has been decreased. Accordingly, the synthetic resin is cured and thus compressed gas G can be prevented from rising through the side surface of the through-hole forming part 40B of the second bushing 40 to circumvent the female mold part 6.

As illustrated in Fig. 6, the present embodiment is configured so that the bottom surface of the outer circumferential part of the cavity S is defined with the mold base part 26 and the male mold part 27, parts 30, 31. protrusions are formed in the corresponding part of the mold base part 26 and male mold part 27 so as to project upwards into the cavity S and when the projecting part 30 and 31 engage with each other the part external side of the upper part of the partially cut protruding part 31, its lower part is firmly in contact while its upper part forms the slot 34. However, the present embodiment is not limited to the previous configuration, but may be realized in another embodiment such as that illustrated in Figs. 10 to 12.

More specifically, as illustrated in Fig. 10, the top surface of the mold base part 26 in a position near the male mold part 27 is provided with a protruding part 30A having a longitudinal section in the form of a right triangle including a vertex angle which projects upwardly into cavity S which is, for example, about 20 to 45 degrees, i.e. e., the projecting portion 30A is formed such that each side surface of the mold base part 26 in contact with the corresponding side surface of the male mold part 27 extends upward and subsequently tilts as extends outwardly to allow its longitudinal plane to be approximately the shape of a right triangle and the slot 34A which is a part of cavity S and has a width that does not allow compressed gas G to enter (for example, an equal width). or less than 0.5 mm) is formed between male mold part 27 and protruding part 30A by partially indenting the outer side of male mold part 27 at the same height as the bottom surface of cavity S (ie, forming a step 27A). In this case, the projecting parts 30A, 31A are formed with a square frame (wire shape) shape in a plan view.

Accordingly, the compressed gas can be prevented from bypassing the female mold part 6 as well as pouring through the space between the mold base part 26 and the female mold part 6, as the molten synthetic resin J penetrates into the mold. slot 34A, can provide satisfactory pressure application by pressing the front surface of the synthetic resin against the cavity forming surface of the female mold part 6 and can cure the melt synthetic resin within the compression time period.

In addition, as illustrated in Fig. 11, the upwardly projecting protruding part 30B into the cavity S and whose longitudinal plane is rectangular in shape is formed in the mold base part 26 at a position next to the mold part 27 male, i. e., the projecting part 30B is formed such that each side surface of the mold base part 26 in contact with the corresponding side surface of the male mold part 27 extends upwardly to form the projecting part 30B having a plane Rectangular longitudinal section and slot 34B which is a part of cavity S and has a width which does not allow compressed gas G to enter (e.g. 0.5 mm or less width) is formed between male mold part 27 and the portion 30B protrudes through the partial cutout of the outer side portion of the male mold portion 27 at the same height as the bottom surface of the cavity S (ie, forming a stepped portion 27A). In this case, the projecting portion 30B is formed with a square frame (wire shape) shape in a plan view.

Accordingly, the compressed gas can be prevented from bypassing the female mold part 6 as well as pouring through the space between the mold base part 26 and the female mold part 6, as the molten synthetic resin J penetrates the groove. 34B, can provide satisfactory pressure application by pressing the front surface of the synthetic resin J against the cavity forming surface of the female mold part 6 and can cure the molten synthetic resin J within the compression time period.

Also, as illustrated in Fig. 12, an upwardly projecting protruding part 30C into the cavity S and whose longitudinal plane is approximately rectangular in shape and whose distal corner portion of the male mold part 27 is blunt is formed in the mold base part 26 in a position near male mold part 27, i. e., the projecting portion 30C is formed such that each side surface of the mold base part 26 in contact with the corresponding side surface of the male mold part 27 extends upwardly and the slot 34C which is a part of the The cavity S and has a width which does not allow compressed gas G to enter (for example, a width of 0.5 mm or less) is formed between the male mold part 27 and the projecting part 30C by the partial cutout of the side part outside of the male mold part 27 at the same height as the bottom surface of cavity S (ie, forming step 27A). In this case, the projecting portion 30C is formed with a square frame (wire shape) shape in a plan view.

Accordingly, the compressed gas can be prevented from bypassing the female mold part 6 as well as pouring through the space between the mold base part 26 and the female mold part 6, as the molten synthetic resin J penetrates into the mold. slot 34C, may provide satisfactory pressure application by pressing the front surface of the synthetic resin J against the cavity forming surface of the female mold part 6 and may cure the molten synthetic resin J within the compression time period.

In the case of forming the molded SJ product as illustrated in Fig. 28 which includes a horizontal X plane, a continuous vertical Z1 plane in communication with the horizontal X plane in the outer circumferential portion of the horizontal X plane in a vertical direction and a Z2 plane continuous vertical plane provided on a posterior surface of the horizontal plane X, the plane Z2 having a cylindrical shape or a square cylindrical shape and being in communication with the horizontal plane X in a vertical direction, or, in the case of forming a molded product without the surface Z1 vertical but with the horizontal surface X and the vertical plane Z2, of course, the technical concept as illustrated in Figs. 6 and 10 to 12. The prior art concept may also be applied to a cavity having a cylindrical space extending in a vertical direction in communication with a space extending in a horizontal direction at a position midway through the outer circumferential part of the space. provided that the cavity is not limited to a configuration consisting of a space extending in a horizontal direction and a cylindrical space extending in a vertical direction in communication with the outer circumferential portion of the space, but to any cavity having a A configuration consisting of a space extending in a horizontal direction and a cylindrical space extending in a vertical direction in communication with the space.

Moreover, in the case of formation of the thin-walled U-part in the molded product as illustrated in Figs. 7 and 8, the first bushing 35 is configured to engage the concave portion formed on the top surface of the male mold part 27 for the first bushing 35 to be secured to the male mold part 27; however, the configuration is not necessarily limited to what was said earlier, i. e. the bushing 35 and the male mold part 27 are not provided separately, but may be configured as a single part as shown in Fig. 13 or a thin wall forming part 35A may be formed in the male mold instead of first bushing 35.

With reference to Figs. 13 and 14, an embodiment will be described in which thin-wall forming part 35A is formed in male mold part 27. Initially, 35A indicates a thin wall forming portion continuously formed on the top surface of the male mold portion 27, whose longitudinal plane has an isosceles trapezoid shape having a shorter upper base and a longer lower base which is configured so that a distance between a surface 42A

of the top part formed in All the part circumference higher gives part Training 35A in thin wall and the i leave 6 of female mold be shorter of what The of others parts for to allow The part formation in U in thin wall in the product molded.

The outer circumferential portion and the inner circumferential portion of the thin wall forming portion 35A are provided with the protruding portions 36A, 37A which penetrate the cavity S and are formed with a square (wire-shaped) frame shape in plan view. and extend upwards to a height lower than the flat surface 42A of the top and incline as they extend inwardly to form their longitudinal plane into an approximately rectangle triangle having a vertex angle of e.g. about 20 to 45 degrees and to form tapered portions 38A, 39A at their top portion. In other words, a height of a transverse portion between oblique side portions forming the protruding portions 36A, 37A and the oblique side portion of the thin wall forming portion 35A having a longitudinal plane with an isosceles trapezoid shape is the same height as the bottom surface of cavity S and the angle formed by both oblique side portions is about 90 degrees, i. e., an approximately right angle and the top portions of the protruding portions 36A, 37A are provided with tapered portions 38A, 39A having good thermal conductivity.

When compressed gas G is injected into cavity S via injection paths 28A, 28B to provide pressure application by pressing the front surface of the melt synthetic resin J against the cavity forming surface of the female mold part 6. compressed gas G arrives at the side surfaces of the thin wall forming portions 36A, 37A protruding so as to contact the side surfaces as shown in Fig. 14A.

In addition, when compressed G gas is injected, the compressed G gas reaches the tapered parts 38A, 39A of the protruding parts 36A, 37A (see Fig. 14B), passes over the tapered parts 38A, 39A (see Fig. 14C). and reaches the base portions of the inclined portions of the protruding portions 36A, 37A, thereby partially reaching the oblique side portion of the thin wall forming portion 35A (see Fig. 14E) or, failing to reach, thereby and partially to the oblique side portion of the thin wall forming part 35A (see Fig. 14D). In this case, the tapered portions 38A, 39A store heat from the fused synthetic resin J.

As a result, the synthetic resin J becomes softer according to the heat stored by the projecting parts 38A, 39A and therefore compressed gas G passes over the projections 36A, 37A to move to a storage bowl defined by the parts. oblique sides of the protruding portions 36A, 37A and oblique side portion of the thin wall forming portion 35A thereby reaching the entire storage basin area (see Fig. 14F).

Therefore, the compressed gas G, having reached the storage basin, pressurizes the molten synthetic resin J so as to push the molten synthetic resin upwards along the oblique side of the thin wall forming part 35A, since a Angle between the oblique side portions 36A, 37A of the protruding portions 36A, 37A and the oblique side portion of the thin wall forming portion 35A is approximately a right angle, can satisfactorily pressurize a portion at which the distance between a portion 42 of the top part of the thin wall forming part 35A and the female mold part 6 is short (narrow) as the synthetic resin J is spread into the part (in Fig. 13, an arrow shows the direction of pressurization) and thus mold transfer irregularities and deformations can be prevented even when the continuous contour having a predetermined width is formed in a Thin-walled, square-frame (wire-shaped) shape on one rear surface side of the molded product. All four sides of the thin-walled U-part may have the same thickness or may have different thicknesses.

As illustrated in Figs. 7 and 8, the present embodiment is configured so that the first bushing 35 is engaged with the concave part formed on a top surface of the male mold part 27 when the thin-walled U-part is formed into a molded product. However, the present embodiment may be configured, as illustrated in Fig. 15, so that the first bushing 35B is engaged with the concave portion formed on the top surface of the male mold part 27 so as to be secured to the 27 part. male mold, which will be described next.

More specifically, in Fig. 15, 35B indicates the first bushing that is configured so that its continuous contour having a predetermined width is engaged with the square (concave) concave portion of the top surface of the part 27. to be secured to the male mold part 27 and the first bushing 35B has an isosceles trapezoid-shaped upper longitudinal plane including a shorter upper base and a longer lower base, has a distance between a surface 42B the top part formed in a complete circumference of the top of the first bushing 35B and the female mold part 6 shorter than that of the other parts and allows the continuous contour having the predetermined width to be formed into a thin-walled U-part in square frame shape (wire type). All four sides of the thin-walled U-part may have the same thickness or may have different thicknesses.

In addition, the lower ends of the oblique side portions of the first bushing 35B whose upper portion is trapezoidal in shape are higher than the bottom surface of the cavity S and the projecting portions 55, 56 whose longitudinal planes including a shorter upper base and a longer bottom base, which penetrate into cavity S, is trapezoidal in shape, including a shorter top base and a longer bottom base (when the oblique sides are elongated, a longitudinal plane is approximately the shape of a right triangle having a (eg, about 20 to 45 degrees) and project at a distance (slots 59A, 59B) from the first bushing 35B of a width that will not allow compressed gas G width equal to or less than 0.5 mm). That is, the projecting portions 55, 56 are formed on the top surface of the male mold portion 27 positioned in the vicinity of the first bushing 35B.

In addition, protruding parts 57 are formed in slightly spaced positions of protruding parts 55 formed with a square (wire-shaped) frame shape in a plan view. The protruding portions 57, 58 that penetrate into the cavity S are formed with a square (wire-shaped) frame shape in a plan view, are in the form of a rectangular triangle in the longitudinal plane with a vertex angle of e.g. about 20 to 45 degrees and extend vertically upwards, sloping as they move toward the bushing 35B. An angle between the oblique sides of the portions 27 and 58 projecting oblique sides of the portions 55, 56 protrude is substantially at right angles, _z ie about 90 degrees. In this case, the bottom surfaces of the grooves 59A, 59B formed between the projecting portions 55, 56 and the first bushing 35B are higher than the bottom surface of the cavity S.

Then, when the compressed gas is injected into the cavity S through the gas injection paths 28A, 28B to provide pressure application by pressurizing the front surface of the molten synthetic resin J against the cavity forming surface of part 6. In a female mold, the compressed gas initially reaches a point where it contacts the vertical side surfaces of the projecting portions 57, 58. When continuing to inject compressed gas, the compressed gas rises until it reaches the top end portions of the projecting portions 57, 58 and then passes over the top end portions to reach the bottom bases of the oblique side portions of the projecting portions. projecting parts 55, 56 to continue to climb the oblique side portions of projecting parts 55, 56.

At the same time, the compressed gas having risen to the oblique side portions of the projecting portions 55, 56 serves to apply pressure in an orthogonal direction to the oblique lateral portions of the projecting portions 55, 56 and in an orthogonal direction to the oblique lateral portions of the projecting portions 57. , 58 protruding (see an arrow of Fig. 15) since an angle between the oblique side portions of the protruding portions 55, 56 and the oblique side portions of the protruding portions 57, 58 is approximately a right angle so that the gas as a result, apply a pressure that pushes the molten synthetic resin J upwards along the oblique side portions of the protruding portions 55, 56 and oblique lateral portion of the first bushing 35B, thereby preventing transfer irregularities from occurring. even where a molded product is provided with the thin walled part, as a satisfactory pressure can be applied while while the molten synthetic resin J spreads upwards to the short (narrow) distance portion between the flat surface 42B of the top part of the first bushing 35B and the female mold part 6.

As described above, in the case where a molded product is provided with the thin wall part, the present embodiment is configured so that the thin wall part whose continuous contour having a predetermined width is in the form of a frame (in formed on a back surface side of the molded product using the first bushing 35 as the thin wall forming part, the thin wall forming part 35A formed in the male mold part 27 and the first bushing 35B as the the thin wall forming part. However, the thin wall portion is not limited to the previous configuration, but may have an H shape that is not a continuous frame shape, may have a cross shape, or may have another shape. In addition, the thin wall portion formed in the molded product may have the same thickness or may have different thicknesses for each straight line.

Still, the present embodiment is not limited to the shape of the protruding part 41 of the second bushing 40 and the shape of the protruding part 44 formed in the male mold part 27, as illustrated in Fig. 9, but may have any other shape, such as illustrated in Figs. 16 to 18.

Initially, as illustrated in Fig. 16, each side surface extends upwardly into the outer circumferential portion of the top surface of the securing portion 40A of the second bushing 40 and slopes as it approaches orifice forming portion 40B. thereby allowing the protruding part 41A, whose longitudinal plane is an approximately rectangle triangle including a vertex angle of, for example, about 20 to 45 degrees and which penetrates into cavity S, protrudes, forming, therein, a slot 53A between the through hole forming part 40B and the projecting part 41A. The protruding part 44A formed to surround the protruding part 41A from the outside is formed so that each side surface of the male mold part 27, which forms the concave part into which the second bushing 40 engages, extends in such a manner tilt as it is directed outwards, thereby allowing the longitudinal plane to be an approximately rectangle triangle having a vertex angle of, for example, about 20 to 45 degrees.

Next, the projecting portion 41A and the projecting portion 44A, which project upwards at the same height and are formed in a square (wire-shaped) frame shape in a plan view, are formed at an end portion of each one of the top surfaces of the corresponding part between the securing part 40A of the second bushing 40 and the male mold part 27 so as to penetrate into the cavity S respectively, an outer lateral part of the upper part of the protruding part 44A is partially cut out and therefore, when the securing part 40A of the second bushing 40 and the male mold part 27 are engaged with each other, the lower parts come into firm contact with one another while the upper part has a slot 54A having a width not allowing compressed gas to enter (for example, a width of 0.5 mm or less). In this case, a depth of the groove 54A defined by the projecting portion 41A of the second bushing 40 and the projecting portion 44A of the male mold portion 27 is formed to be slightly less than a depth of the cavity S.

Then, when compressed gas is injected into cavity S through gas injection paths 28A, 28B to form a through-hole in a molded product, the molten synthetic resin J passes over the protruding part 44A of the top surface of the molded part. 27 of a male mold when pressurized by the compressed gas to reach the slot 54A defined by the projecting part 44A and projecting part 41A and the slot 53A defined by the through hole forming part 40B and projecting part 41A of the second bushing 40.

In this case, the compressed gas G within the cavity S is collected in the compression tank 47 through the small gap between the male mold part 27 and the second bushing 40 and the outlet and inlet path 49 so as not to escape. applying excessive pressure to a part in which the synthetic resin J is pressurized against the cavity forming side of the female mold part 6 by the compressed gas G. On the other hand, the compressed gas collected in the compression tank 47 is supplied to cavity S through the small space and the outlet and inlet path 49 so that the compressed gas can be

spread to satisfactory. an where the applied pressure does not was As described previously, a gas flow G tablet is suspended using the deposit effect 47 in

compression or allowing the synthetic resin to penetrate the slots 53A, 54A, thereby flowing the compressed gas G to other parts to increase a volume of the compressed gas G within cavity S for the purpose of molding and, In this way, the density of the synthetic resin around the through hole (opening portion) of the molded product can be increased. Consequently, the pressure around the through-hole (opening part) rises due to pressurization and the temperature of the synthetic resin decreases due to the male mold part 27 whose temperature has been decreased. Accordingly, the synthetic resin is cured and thus compressed gas G can be prevented from circumventing the female mold part 6 by the fact that the compressed gas G rises over the side surface of the through hole forming part 40B of the second one. bushing 40.

Furthermore, as illustrated in Fig. 17, the protruding part 41B, which has a longitudinal arc-shaped plane and penetrates into cavity S, is formed such that each side surface extends around the outer circumferential part of the surface. top of the securing portion 40A of the second bushing 40 so as to fall as it approaches the through hole forming part 40B, and thereby the groove 53B forms between the through hole forming part 40B and the through hole part 40B. 41B protruding. The projecting portion 44B formed to surround the projecting portion 41B from the outside is configured so that each side surface of the male mold portion 27 forming the concave portion receiving the second bushing 40 extends and descends as it is directed. thereby allowing its longitudinal plane to be arc-shaped.

Then, the projecting part 41B and the projecting part 44B projecting upwards to the same height to penetrate cavity S respectively are formed to have the shape of a square (wire-shaped) frame in a plan view at an end portion of each top surface of the corresponding portion between the securing portion 40A of the second bushing 40 and the male mold portion 27 and the outer side portion of the top portion of the protruding portion 44B is partially cut out and, therefore, when the securing part 40A of the second bushing 40 and the male mold part 27 engage with each other, the lower parts come into close contact with one another, while the upper part is provided with the slot 54B having a width not allowing compressed gas G to enter (for example, a width of 0.5 mm or less). In this case, a depth of the groove 54B defined by the projecting portion 41B of the second bushing 40 and the projecting portion 44B of the male mold part 27 is formed to be slightly less than a depth of the cavity S.

Then, when compressed gas is injected into cavity S through gas injection paths 28A, 28B to form a through-hole in a molded product, the molten synthetic resin J passes over the protruding part 44B of the top surface of the molded part. 27 of a male mold when pressurized by the compressed gas to reach the slot 5BA defined by the projecting part 44B and projecting part 41B and the slot 53B defined by the through hole forming part 40B and projecting part 41B of the second bushing 40.

In this case, the compressed gas G within cavity S is collected in the compression tank 47 through a small gap between the male mold part 27 and the second bushing 40 and the outlet and inlet path 49 so as not to apply a excessive pressure, greater than necessary, to a part in which the synthetic resin J is pressurized against the cavity forming side of the female mold part 6 by the compressed gas G. On the other hand, the compressed gas collected in the compression tank 47 is supplied to the cavity S through the small space and the outlet and inlet path 49 to allow the compressed gas to pressurize an unsatisfactorily pressurized part.

As described above, a flow of the compressed G gas is suspended by using an effect of the compression tank 47 or by allowing the synthetic resin to penetrate the slots 53B, 54B, thereby compressed G gas is largely flowed to the others. parts in order to increase a volume of compressed gas G within cavity S in order to apply pressure to the synthetic resin, thereby increasing the density of the synthetic resin around the mold. Consequently, from the through hole of the product the pressure around the through hole (opening part) rises due to pressurization and the temperature of the synthetic resin decreases due to the male mold part 27 whose temperature has been decreased. Accordingly, the synthetic resin is cured and, by compressing G-gas thereby circumventing, the female mold part 6 can be prevented as compressed G-gas rises over the side surface of the through-hole forming part 40B of the second. bushing 40.

In addition, as illustrated in Fig. 18, a protruding part 41C, which has a longitudinal plane in the shape of an approximately rectangular triangle having a vertex angle of, for example, about 20 to 45 degrees and penetrates into cavity S, is formed such that each side surface extends around the outer circumferential portion of the top surface of the securing portion 40A of the second bushing 40 and slopes as it approaches the through-hole forming portion 40B and thereby In this way, a groove 53C is formed between the through-hole forming 40B and the protruding portion 41C formed in the shape of a square (wire-shaped) frame in plan view.

When compressed gas G is injected into cavity S through injection paths 28A, 28B to form a through-hole in a molded product, the melt synthetic resin contacts the projecting portion 41C of the second bushing 40 due to the pressure applied by the compressed gas, thereby preventing synthetic resin J from circumventing female mold part 6.

More specifically, especially when the second bushing 40, as a through-hole forming part, is positioned away from the gas injection paths 28A, 28B, if the volume of compressed gas G within cavity S increases to increase the density of the synthetic J resin, i. e. If the compressed gas G can apply upward pressure around the second bushing 40, it is no longer necessary to provide the protruding part in the male mold part 27 and, as a result, the synthetic resin can be prevented from circumventing. the female mold part 6 only with the projecting part 41C of the second bushing 40.

However, as described above, it is necessary that the compressed gas G within cavity S is collected in the compression vessel 47 through a small gap between the male mold part 27 and the second bushing 40 so as not to apply pressure. excess, greater than necessary, to a part in which the synthetic resin J is pressurized against the cavity forming side of the female mold part 6 by the compressed gas G and, on the other hand, the compressed gas collected in the compression tank 47 is supplied to cavity S through the small space to allow compressed gas to spread through an unsatisfactorily pressurized portion.

The above embodiment exemplifies the formation of a molded product whose cavity S is in the form of a box top cap (having a rectangular horizontal surface and four vertical surfaces extending vertically downwards from each side of the horizontal surface). ). Another embodiment of forming a plate shaped product will be described below with reference to Figs. 19 to 22.

Initially, an approximately cuboid bushing 65 is engaged with the concave portion formed in the male mold part 27 to be secured therein, and cavity S is defined by the female mold part 6, bushing 65 and male mold part 27. A top surface of bushing 65 is slightly smaller than the bottom surface of cavity S i. e., the bottom surface of cavity S is defined by a portion of the circumferential edge portion of an opening of the top surface of the male mold portion and the bushing 65. In addition, each side surface extends upwardly in the outer circumferential portion of the top surface of the bushing 65 sloping inwardly to thereby allow the protruding portion 60, the longitudinal plane of which is approximately the shape of a right triangle including a vertex angle of , for example, about 20 to 45 degrees that penetrates into the projecting cavity S and is formed with a square (wire-shaped) frame shape in a plan view, thereby forming slot 61 having a width that does not allow compressed gas G (e.g., a width of 0.5 mm or less) to enter between the female mold part 6 and the projecting part 60. The projecting part 44A formed to surround the projecting part 41A from the outside is formed so that each side surface of the male mold part 27, which forms the concave part into which the second bushing 40 engages, extends so as to tilt it extends outwards, thereby allowing the longitudinal plane to be approximately the shape of a right-angled triangle having a vertex angle of, for example, about 20 to 45 degrees.

However, as described above, it is not always necessary to provide the projecting portion 60 throughout the outer circumferential portion of the top surface of the bushing 65 or to form the slot 61 throughout the gap between the projecting portion 60 and the female mold portion 6. but these may be provided partly on the outer circumferential portion of the horizontal portion where the compressed gas tends to spread easily from the molded product to thereby prevent the compressed gas from circumventing the front surface of the mold part 6. female. More specifically, they may be provided only in parts (zones) in which the compressed gas may exit outside the injection molding equipment when the compressed gas bypasses the front surface of the female mold part 6.

When compressed gas from the compressed gas source is supplied to cavity S via a feed valve and a gas injection path 28C upon injection of a predetermined amount of synthetic resin J fused into cavity S, a layer is formed. of compressed gas between the molten synthetic resin J which was injected into cavity S and bushing 65 (see Fig. 21).

In addition, when the compressed gas continues to be injected, the molten synthetic resin J reaches the outer circumferential portion of the cavity S to pass over the oblique portion of the protruding portion 60 and into the groove 61. Accordingly, it is prevented that compressed gas travels outwards because molten synthetic resin has penetrated the

slot 61 and from that thus prevented if the compressed gas outline the surface front of part 6 female mold (see Fig. , 22).

In this case, the compressed gas G within the cavity S is collected in the compression tank 47 through a small gap between the male mold part 27 and the bushing 65 and an outlet and inlet path 67 so as not to apply a excessive pressure, greater than necessary, to a part in which the synthetic resin J is pressurized against the cavity forming side of the female mold part 6 by the compressed gas G. On the other hand, the compressed gas collected in the compression tank 47 is supplied to cavity S through the small space and the outlet and inlet path 67 so that the compressed gas can spread to a part where pressure is not applied. satisfactory. Accordingly, the compressed gas may be prevented from bypassing the female mold part 6 and exiting the injection molding equipment through the space between the female mold part 6 and the male mold part 27 and may be provided a satisfactory pressure application by pressurizing the front surface of the synthetic resin against the cavity forming surface of the female mold part 6.

The embodiment described above describes a case of forming a plate-shaped product, wherein the protruding portion 60 that penetrates into cavity S is projected from the outer circumferential portion 60 of the top surface of the bushing 65 and is formed. the slot 61 between the female mold part 6 and the projecting part 60. Another embodiment of forming a molded product whose cavity S is in the form of a box-shaped top cover (having a rectangular horizontal surface and four vertical surfaces extending vertically downwards from each side of the horizontal surface) and wherein the compressed gas can be prevented as far as possible from being described below with reference to Figs. 23 to 26.

Initially, an approximately cuboidal bushing 66 is engaged with the concave portion formed in the male mold part 27 and attached thereto, cavity S is defined by the female mold part 6, male mold bushing 66 and part 27 and a bottom surface of the cavity. S is defined by bushing 66 and male mold part 27.

More specifically, an upwardly extending protruding portion 62 is formed in a slightly inward position with respect to the outer circumferential end portion of

6 is a top surface of the bushing 66 and inclines as it approaches the interior to allow a longitudinal plane thereof to be approximately the shape of a right triangle including a vertex angle of, for example, about 20 to 45 degrees penetrating the vertex angle into cavity S. In addition, each side surface extends upwardly at a circumferential edge portion of an opening of the top surface of the male mold part 27 forming a concave part of the part 27 of a male mold to form the concave portion and then a protruding portion 63 is formed therein to incline as it approaches its exterior to penetrate into the cavity S and has a longitudinal plane with the approximate shape of a right-angled triangle including a vertex angle of, for example, about 20 to 45 degrees. In this case, the protruding part 63 is higher than the protruding part 62 and a groove 64 having a width that does not allow compressed gas G to enter (e.g., a width of 0.5 mm or less) is formed between the protruding part 62 of the bushing 66 and the protruding part 63 of the male mold part 27. The protruding parts 62, 63 are formed in the form of a continuous square (wireframe) frame in a plan view, which, however, is not limiting, but the protruding parts 62, 63 may be discontinuous and may only be provided in a part (zone) in which the compressed gas may circumvent the front surface of the male mold part 27 to thereby cause a leakage of the compressed gas out of the injection molding equipment.

When a predetermined amount of molten synthetic resin J is injected into cavity S, the molten synthetic resin J passes over the oblique side portion of the protruding portion 63 to partially penetrate slot 64 (see Fig. 24) and subsequently when compressed gas is supplied to cavity S from the compressed gas source through the supply valve and a gas injection path 28D forms a layer of compressed gas between the molten synthetic resin J having been injected into cavity S and the bushing 66 (see Fig. 25).

Further, when the compressed gas is injected, the compressed gas reaches the upper part of the protruding part 62 of the bushing 66; however, since the protruding part 63 of the male mold part 27 is positioned higher than that of the protruding part 62 of the bushing 66, the compressed gas can apply pressure without passing over the protruding part 63 (see Figs 26 and 27).

In other words, as described above, since the protruding part of the male mold part 27 is in a higher position than the protruding part 62 of the bushing 66, the melt synthetic resin that has penetrated into slot 64 does not separate from the melt synthetic resin. which did not penetrate into slot 64 even at the time of pressure applied to the synthetic resin J by the compressed gas. Accordingly, if the molten synthetic resin J separates, the compressed gas may pass over the protruding portions 62 to circumvent the front surface of the male mold part 27, thereby causing an outflow of the compressed gas. injection molding equipment.

However, with the above configuration, the compressed gas can be prevented from turning and can provide satisfactory pressure application so that the melt synthetic resin can be cured within the time period during which the synthetic resin is pressurized. fused.

The present invention has been described with reference to embodiments; However, one skilled in the art may design various alternatives, changes and modifications without departing from the spirit and scope of the invention. It is to be understood that the present invention encompasses the aforementioned alternatives, changes and modifications without departing from the spirit and scope of the invention.

Claims (4)

1. Injection molding method for injecting a molten synthetic resin into a cavity formed between a female mold and a male mold, after heating a cavity forming surface side of the female mold, inject compressed gas into a space between a posterior side of the resin. and a cavity forming surface of the male mold, and provide molding by pressing a front surface of the synthetic resin against the cavity forming surface of the female mold, comprising the steps of: when a plurality of bushings to form a thin wall part or an opening part, or both, in a molded product is provided in a concave part formed on a top surface of the male mold, collecting the injected compressed gas into the cavity in a tank through a space between a bushing and the male mold, so as not to provide excessive compression, greater than necessary, over a part where the synthetic resin can be pressurized against the cavity forming surface of the female mold, while the compressed gas collected in the The tank is provided, through a gap between the other bushing and the male mold, to a part where insufficient compression of the compressed gas is applied. 2. Injection molding equipment which is configured to inject a molten synthetic resin into a cavity formed between a female mold and a male mold after heating a cavity forming surface side of the female mold, inject compressed gas into a space between a back surface. of the synthetic resin and a cavity forming surface of the male mold and provide molding by pressing a front surface of the synthetic resin against the cavity forming surface of the female mold, characterized in that: a bottom surface of the cavity is comprised of a bottom surface forming part and the male mold, an upwardly projecting protruding portion so as to penetrate the cavity is formed at least one end surface portion of top of the bottom surface forming part of a joint part between the bottom surface forming part and the male mold so as to be formed into a frame shape along the joint part, and a groove between the projecting portion and the male mold. 3 Molding Equipment injection of according to claim 2, characterized per: the cavity consists of a space that extends into a horizontal direction and a cylindrical space what forms a continuity with this space and extending in a vertical direction and a bottom surface of a cylindrical part of the cavity is constituted by a mold base portion which serves as the bottom surface forming part by the mold base portion at the which male mold is attached, and by the male mold; and wherein an upwardly projecting protruding portion into the cavity is formed along a joining portion to be formed in a frame shape at a top surface end portion of the mold base portion at the coupling part with the male mold, and a groove is formed between the projecting part and the male mold. Injection molding equipment according to claim 2, characterized in that: the cavity is comprised of a space extending in a horizontal direction and a cylindrical space forming a continuity with this space and extending in a vertical direction, and a bottom surface of a cylindrical part of the cavity consisting of a base part mold serving as the bottom surface forming part, the mold base part to which the male mold is attached, and the male mold; and wherein an upwardly projecting protruding part to the cavity is formed at each top surface end portion of a joint part between the mold base part and the male mold so as to be formed into a frame shape along the joint portion, and both projecting portions provide a groove in an upper portion when both projecting portions engage with each other. Injection molding equipment according to claim 2, characterized in that: a bushing that penetrates the cavity is engaged with a concave portion formed on a top surface of the male mold to be secured therein; wherein a bottom surface forming section forming a bottom surface of the cavity with the male mold is formed in an outer circumferential portion of the bushing, and a first protruding part that penetrates the cavity is formed in a top surface end portion. of the bottom surface forming section; wherein a second protruding part that penetrates into the cavity is formed on a top surface of the male mold to surround the first protruding part on the outside, and wherein a groove is formed between the second protruding part and the first protruding part. 6 Equipment of claim 2, injection molding characterized by: in wake up with the a bushing that penetrates the cavity and contacts the female mold to whose part form a top part of opening in a molded product, engaging a concave portion formed on a top surface of the male mold to be secured therein; wherein a bottom surface forming section forming a bottom surface of the cavity with the male mold is formed in an outer circumferential portion of the bushing and a first protruding part that penetrates the cavity is formed in a top surface end portion of the bushing. bottom surface forming section; wherein a second protruding part that penetrates into the cavity is formed on a top surface of the male mold to surround the first protruding part on the outside, and wherein a groove is formed between the second protruding part and the first protruding part. Injection molding equipment according to claim 2, characterized in that: a bushing serving as the bottom surface forming portion to be engaged with a concave portion formed on a top surface of the male mold to be secured therein; wherein a first hollow-penetrating protruding part is formed on a top surface end portion of the bushing top surface along a male mold joining portion, and a second hollow-penetrating protruding part is formed on a cavity-forming top portion. circumferential edge of an opening forming the concave portion on the top surface of the male mold, the second projecting portion projecting at a higher height than the first projecting portion; and wherein a groove is formed between the second projecting part and the first projecting part.