JPH08267517A - Mold structure - Google Patents

Abstract

PURPOSE: To realize the increase of the number of articles to be molded per unit area of molded articles by a method wherein the parting face area of a mold is made larger than its crosssectional area. CONSTITUTION: The mold parting face areas 15 and 22 of a pair of molds 11 and 13 are parted into a plurality of faces 15a, 15b... 22a, 22b... tilted to a mold opening and closing direction (b) so as to form molding cavities 18a, 18b... 23a, 23b... on the tilted faces. The mold parting faces are formed in ridges 16 and valleys 17 in zigzags or in cones or pyramids. Thus, since the parting lines emerging on a molded article can be located on the faces excluding the faces, through which the molded article contacts with other component, the durability of the molds can be improved and their heating efficiencies and evacuating efficiencies can be enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold structure used for injection molding of rubber or resin.

[0002]

2. Description of the Related Art FIGS. 13 and 14 show a typical conventional mold structure, in which 1 is a fixed mold and 2 is a movable mold which is opened and closed with respect to the fixed mold 1 (shown by an arrow a). Then, each is fixed to the mold mounting plates 3 and 4 of the injection molding machine. Reference numeral 5 denotes a mold dividing surface of both molds 1 and 2, and a molding cavity 6 is formed on this surface.
Are formed. Reference numeral 7 is a sprue provided on the movable mold 2 side, and 8 is a nozzle that abuts on the sprue 7 and injects heat-softened rubber or resin into the cavity 6. At the time of molding, resin or rubber is injected into the cavity 6 from the nozzle 8 with the molds 1 and 2 clamped. After the molding is completed, the movable mold 2 moves to the left in the figure, the molds 1 and 2 are opened, and the molded product is taken out. In the figure, 9 is a fine groove for vacuum suction formed around the cavity 6, and 10 is a heater embedded in the mold 1 below the mold dividing surface 5.

[0003]

In the mold structure described above, the sizes of the molds 1 and 2 are limited by the sizes of the mold mounting plates 3 and 4 of the molding machine to which they are mounted, and the mold 1 Since the mold dividing surface 5 of No. 2 is perpendicular to the mold opening / closing direction a, the area of the dividing surface cannot be increased beyond the sectional area of the molds 1 and 2. Therefore, the number of molded products taken is
There is a problem that it is limited by the area of the die mounting surface and cannot be increased, which lowers the production efficiency.

Further, in the molded product produced by the above mold structure,
The mold parting line appearing on the surface often coincides with the contact surface with other parts, causing a problem such as deterioration of durability.

The present invention has been made in view of the above circumstances, and it is possible to increase the divided surface area of a die beyond the cross-sectional area of the die. Therefore, the number of moldings per unit area can be increased. The present invention provides a mold structure capable of increasing the temperature of the mold.

Further, according to the present invention, the position of the mold parting line appearing in the molded product can be set on the surface which does not come into contact with other parts, so that the durability of the molded product and the quality thereof can be improved. It provides the type structure.

[0007]

According to the present invention, in a pair of molds having a mold dividing surface in which a molding cavity is formed, the mold dividing surface is formed into a surface inclined with respect to the opening / closing direction of the mold. And a molding cavity is provided on the inclined surface.

Further, in the present invention, the die dividing surface is formed in a zigzag cross-section having peaks and valleys, and the inclined surface is formed by an inclined surface between the peaks and valleys. The molding cavity may be provided on the inclined surface.

Further, in the present invention, the mold dividing surface may be formed in a conical surface shape, and the molding cavity may be formed in the conical surface.

Further, in the present invention, the mold dividing surface may be formed in a pyramidal surface shape, and the molding cavity may be formed in the pyramidal surface.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS.
It will be described based on. This example is a mold for manufacturing rectangular parallelepiped rubber. In the figure, 11 is a fixed mold attached to a mold fixing plate 12 of an injection molding machine (not shown), and 13 is a mold fixing plate 14 of the injection molding machine facing the fixed mold 11. The movable mold thus formed is brought into pressure contact with the fixed mold 11 at the time of molding, and after molding, it is moved upward in the drawing. The opening / closing direction of the movable mold 13 is indicated by an arrow b.

The mold dividing surface 15 of the fixed mold 11 has a plurality of surfaces 15a, 1 inclined with respect to the opening / closing direction b of the movable mold 13.
It is divided into 5b ,. That is, the mold dividing surface 15
Are formed to have a zigzag cross-section formed by the peaks 16 and the valleys 17, and the surfaces 15a, 15b, ... Are formed by the inclined surfaces between the peaks 16 and the valleys 17. 18a, 18
b, ... Are molding cavities formed on the surfaces 15a, 15b ,. Three cavities 18a, 18a, 18a are formed on one surface 15a. 1
9 and 19 are heaters embedded in the peaks 16 and 16, and 20 are pores communicating with the valleys 17 and are connected to a vacuum pump (not shown), and cavities 18a, 18b ,. Vacuum suction. Reference numeral 21 is a heat insulating material that covers the outer periphery of the fixed mold 11.

The mold dividing surface 22 of the movable mold 13 is formed in a shape corresponding to the mold dividing surface 15 of the fixed mold 11, and therefore when the molds 11 and 13 are clamped, the mold dividing surface 15 is formed. , 22 are in close contact. Surfaces 22a, 2 inclined with respect to the mold opening / closing direction b
Mold cavities 23a, 23b, ... Are formed in 2b ,. Similar to the fixed mold 11, three cavities 23a, 23a, 23a are formed on one surface 22a. 24, 25 and 26 are cavities 23a,
23b, .. Sprue supplying rubber or resin material,
Runner and gate. 27 is a mountain part, 28 is a valley part, 2
9 and 29. are heaters embedded in the mountain portion 29, and 30 is a heat insulating material that covers the outer periphery of the movable mold 13. 31 is
It is a nozzle for injecting the unvulcanized rubber that has been softened by heating from the sprue 24.

In the above structure, two molds 1 are used for molding.
Heaters 1 and 13 are heated to vulcanization temperatures by heaters 19 and 29, and movable mold 13 is brought into contact with fixed mold 11 and clamped. At this time, simultaneously from the pores 20 to the mold dividing surface 1
5, 22 and cavities 18a, 18b, ... 23a,
Air of 23b, ... Is discharged to the outside. The vacuum suction serves to prevent air bubbles from being mixed in the molded product. The unvulcanized rubber softened in this state is passed through the sprue 24, the runner 25, and the gate 26 to form the cavities 18a, 18
b, .. 23a, 23b ,. After the rubber is injected at a predetermined pressure and a predetermined time required for vulcanization elapses, that is, after the molding is completed, the movable mold 13 is moved upward in the drawing and the molds 11 and 13 are opened. After that, the rectangular parallelepiped rubber 32 (FIG. 3), which is a molded product, is transferred to the molds 11 and 1.
Taken out from 3. When the operator removes the rectangular parallelepiped rubber 32 from the mold 11, the work is easy because the rectangular parallelepiped rubber 32 partially projects from the mold dividing surface 15a.

Further, the shape of the mold is longer than that of the conventional mold in the mold opening / closing direction, so that the outer area of the mold is increased. By covering the outside of this mold with a heat insulating material. The heat insulating effect is increased, and the heating efficiency can be improved also from this point.

As shown in FIG. 4, the inclination angle θ of the surface 15a
Is set corresponding to the height h of the rectangular parallelepiped rubber 32 to be molded. That is, if the height h is large, the angle θ may be set small, and if the height h is small, the angle θ may be set large.

FIGS. 5 to 7 show a second embodiment of the present invention and show a mold structure for manufacturing a plurality of rubber O-rings 33 having different diameters. In the figure, 34 is a fixed mold, 35 is a movable mold, 36 is a conical body formed on a mold dividing surface 37 of the fixed mold 34, the surface of which constitutes a part of the mold dividing surface 37. 38 is a conical concave portion formed in the movable mold 35 so as to correspond to the conical body 36, and 39a, 39b, 39c are
A molding cavity formed on the surface of the cone, 40 is a fine hole for vacuum suction provided in the fixed mold 34, 41a,
41b and 41c are cavities 39a, 39b and 39, respectively.
It is a gate for injecting resin or rubber into c. 51 is
It is a heater. A plurality of the conical bodies 36 can be formed on the fixed mold 34.

As shown in FIG. 8, the mold dividing line of the O-ring 33 manufactured by the mold according to the above embodiment is a line inclined with respect to the horizontal direction as shown by a broken line c. On the other hand, the dividing line manufactured by the conventional mold is a line which is aligned in the horizontal direction as shown by a broken line d, and a rubber piece called a line or a burr appears at the portion corresponding to the dividing lines c and d. If this coincides with the contact surface, there is a problem that a smooth contact cannot be obtained and a crack is easily generated from this portion. Therefore, the O-ring having the dividing line d that coincides with the contact surfaces e and f as in the conventional example has a structural problem, and the dividing line c does not overlap the contact surfaces e and f as in this example.
It is important for the characteristics of the O-ring. Since the mold having the above structure corresponds to a molded product when the mold is opened, the product molded by this mold is limited to elastic rubber or elastomer.

FIGS. 9 to 11 show a third embodiment of the present invention and show a mold structure for manufacturing a quadrangular rubber packing 42. 43 is a fixed mold, 44 is a movable mold, 45
Is a quadrangular pyramid formed on the mold dividing surface 46 of the fixed mold 43, and the surface thereof forms a part of the mold dividing surface 46. 47
Is a pyramidal recess formed in the movable mold 44 so as to correspond to the pyramid 45, 48a and 48b are molding cavities formed on the surface of the pyramid, and 49 is a vacuum provided in the fixed mold 43. Pores for suction, 50a and 50b are gates for injecting resin or rubber into the cavities 48a and 48b, and 52 is a heater. The pyramid 45 is a fixed mold 4
3 can be formed in plural.

As shown in FIG. 12, the mold dividing line of the packing 42 manufactured by the mold according to the above embodiment is a broken line g.
As shown in, it matches the diagonal line of the packing cross section. On the other hand, the dividing line manufactured by the conventional mold is a line which is aligned in the horizontal direction as shown by the broken line h, and rubber pieces called lines or burrs appear at the portions corresponding to the dividing lines g and h. If this coincides with the contact surface with other parts, there is a problem that smooth contact cannot be obtained and cracks are likely to occur from this part. Therefore, the packing in which lines or burrs appear on the inner surface and the outer surface as in the conventional example has a structural problem, and it is important for the characteristics of the packing that the dividing line g does not appear on the inner and outer surfaces of the packing as in this example.

In the above embodiment, the injection molding of the rubber material has been described, but it goes without saying that the invention can be applied to the injection molding of the resin material. Further, in the third embodiment described above,
Although the case where the quadrangular pyramid is used has been described, various polygonal pyramids can be used depending on the application.

[0022]

As described above, according to the present invention, since the mold dividing surface is formed on the surface inclined with respect to the opening / closing direction of the mold, and the molding cavity is formed on this inclined surface, the mold dividing surface is formed. It is possible to increase the area of, and thus increase the number of molded articles to be taken. This increase in the number of molded products can be increased by 1.5 to 2 times as compared with a conventional mold having the same cross-sectional area.

Further, according to the present invention, when the die dividing surface has a zigzag cross section composed of peaks and valleys, the gate can be positioned on the top of the peaks, so that the sprue can be shortened. As a result, a small amount of rubber or resin material remaining on the sprue can be used.

Further, according to the present invention, since the heater is embedded in the mountain portion and the two inclined surfaces are heated, the heating efficiency of the mold can be improved. That is, in the past, the heater was embedded in the mold on the flat mold dividing surface, but in such a structure, only one mold dividing surface could be heated, and the heating efficiency was poor. According to the inventor's experiment, it was confirmed that the heating efficiency was improved by about 15%.

Further, according to the present invention, since the pores for vacuum suction are provided at the bottom of the valley portion, the length of the pores is longer than that of the narrow groove provided around the cavity of the mold dividing surface in the related art. It is possible to shorten the suction time and improve the suction efficiency.

Further, according to the present invention, when molding the O-ring or the rectangular packing, it is possible to position the dividing line on the surface of the O-ring or the rectangular packing which does not come into contact with other parts, and thus the O-ring or the rectangular packing. The durability of can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view for explaining a first embodiment of the present invention.

FIG. 2 is a perspective view showing a part of a mold dividing surface of a fixed mold in the embodiment.

FIG. 3 is a perspective view showing a molded product in the example.

FIG. 4 is a cross-sectional view showing the main parts of the embodiment.

FIG. 5 is a sectional view for explaining a second embodiment of the present invention.

FIG. 6 is a perspective view showing a part of a mold dividing surface of the fixed mold in the embodiment.

FIG. 7 is a perspective view showing a molded product in the example.

FIG. 8 is a cross-sectional view showing a molded product in the same example.

FIG. 9 is a sectional view for explaining a third embodiment of the present invention.

FIG. 10 is a perspective view showing a part of a mold dividing surface of the fixed mold in the embodiment.

FIG. 11 is a perspective view showing a molded product in the example.

FIG. 12 is a cross-sectional view showing a molded product in the same example.

FIG. 13 is a cross-sectional view for explaining a conventional example.

FIG. 14 is a cross-sectional perspective view of a fixed mold in the conventional example.

[Explanation of symbols]

11, 34, 43 ... Fixed mold 12, 14 ... Mold mounting plate 13, 35, 44 ... Movable mold 15, 22, 37, 46 ... Mold split surface 16, 27 ... ...... Yamabe 17,28 ...... Tanibe 18a, 18b..23a, 23b..39a, 39b..4
8a, 48b ..... Cavity 19,29 ..... Heater 20, 40, 49 ..... Pore 21,30 ..... Heat insulating material 31 ..... Nozzle 33 ..... O-ring 36 .. Body 38 ... Recess 42 ... Rubber packing 45 ... Pyramidal body

Claims (6)

[Claims] 1. A pair of molds having a mold dividing surface in which a molding cavity is formed, wherein the mold dividing surface is formed on a surface inclined with respect to the opening / closing direction of the mold, and the molding cavity is formed on the inclined surface. Mold structure characterized by being provided with 2. The mold dividing surface has a zigzag cross section composed of peaks and valleys, and the inclined surface is formed by an inclined surface between the peaks and valleys, and the inclined surface has the above-mentioned shape. The mold structure according to claim 1, wherein a molding cavity is provided. 3. The mold structure according to claim 1, wherein a heater is embedded inside the mountain portion. 4. The mold structure according to claim 1 or 2, wherein pores for vacuum suction are located at the bottom of the valley. 5. The mold structure according to claim 1, wherein the mold dividing surface is formed in a conical body surface shape, and the molding cavity is formed in the conical body surface. 6. The mold structure according to claim 1, wherein the mold dividing surface is formed in a pyramidal surface shape, and the molding cavity is formed in the pyramidal surface.