JPS63134207A - Vulcanizing mold for tire and manufacture thereof - Google Patents

Abstract

PURPOSE:To vent during vulcanizing smoothly and leave no residues of vulcanized rubber by utilizing a pore forming component formed by bonding each of the ends of tapered metallic components and buried in a rib and drawing rubber out of both ends of said pores after vulcanizing. CONSTITUTION:As the central part of a pore forming component 8 is held firmly to a rib 16, the same moves from a core 1 to a mold 15 and its both ends come out of a filling material and protrude out of the outer face of the rib 16. Then, the pore forming component 8 protruding out of the outer face of the rib 16 is drawn out of the rib 16. By vulcanizing a raw tire by means of said mold 15, gas and air generated during vulcanizing are drawn out and also raw rubber flowing from the both openings into a vent hole 17 is cut in the central step section of the vent hole 17 and drawn out when removing the tire, to leave no residues of rubber in the vent hole.

Description

DETAILED DESCRIPTION OF THE INVENTION 1''/1 The present invention relates to a method for manufacturing a vulcanized tire mold having pores in the bone portion.

In general, tire vulcanization molds have a large number of so-called vent holes that extend in the radial direction and have small diameters to vent gas generated from the green tire during vulcanization. Therefore, it protruded from the outer surface of the vulcanized tire.

A large number of so-called spews are formed. Since such spills disturb the appearance of the finished tire, they are cut and removed by a picker in a subsequent process, but such cutting and removal work is extremely troublesome. For this purpose, a vent hole extending approximately in the axial direction of the tire is formed in the protruding bone part of the mold that corresponds to the groove on the tire tread and shoulder surface.
It has been desired to form spills within the grooves of product tires. As a method for forming such a bent ball of a mold, an invention described in Japanese Patent Application Laid-Open No. 141351/1983 has been proposed as L7. However, since the pores (ventholes) in the bone part disclosed in this publication are cylindrical, when a tire is vulcanized using a tire vulcanization mold manufactured by this method, the rubber that has flowed into the pores When the tire was removed from the mold after vulcanization, it was easy to break near both exits (openings at both ends) of the pores. Also, No. 5 of Special Publication No. 46-2412G
It is also possible to use the pores shown in the figure, but in order to form holes in which the central part becomes relatively narrow near both exits, machining of the mold 2.
For example, there is a method of drilling with a hand drill, or a mold is made using a water-soluble part key with a constricted center part instead of the linear body 8 described in Japanese Patent Application Laid-open No. 60-141351. A possible method is to unravel this water-soluble member from the mold to form pores.

However, in the method described in JP-A No. 60-141351, the rubber that has flowed into the pores of the bone is removed from the mold after vulcanization. When taking out the tire from the tire, there is a problem that if the rubber is cut near both exits of the pores and rubber remains in the pores, the gas release effect cannot be achieved. In addition, method (1) has problems such as poor workability and difficulty in making narrow holes. In addition, in the method (2) above, due to the strength constraints of the water-soluble member, the center part (convergent part) must be made with a diameter of 1.3 mm or less.

Because the rubber is difficult to cut in the center, JP-A-60-141
It had the same problem as No. 351.

Also, due to limitations in manufacturing technology for water-soluble parts, the width of the bone part was 8.
There was a problem in that it was difficult to form a shape with a constricted center part when applied to objects with a diameter of mm or more.

The first problem is that the inner peripheral surface has a bone portion corresponding to the tire tread and the groove on the shoulder surface, and this bone portion has A contour with a stepped part at the converging part in the center of the long plane.
The vulcanized mold for tires is characterized by having a vent hole that is almost flat with the surface.Secondly, it has grooves on the outer peripheral surface that have the same shape as the tread and shoulder surface of the product tire, and also has grooves on the outer circumferential surface that have the same shape as the tread and shoulder surfaces of the product tire. A process of preparing a core in which many pairs of recesses are formed in opposing side walls, and a pore-forming member in which a stepped part is formed in the converging part by joining the tips of two tapered members. a step of inserting and burying both ends into the recesses of each of the moons and bridging the grooves with the pore-forming member; and surrounding the core with a main mold between the inner surface of the main mold and the outer surface of the core. a step of forming a mold by injecting and solidifying molten metal into the hollow portion, and casting a central portion of the porous molded member into the bone portion of the mold solidified within the groove; , after dividing the mold from the core and the main die, extracting tapered members from both sides of the bone portion of the mold to form pores in the bone portion of the mold. This problem can be solved by a method for manufacturing a vulcanized tire mold.

1. In this invention, the pore-forming member, which is formed by joining the tips of the tapered metal members embedded in the bone part to form a stepped part, can be pulled out from both sides of the mold to easily center the pore-forming member. It is possible to make a tire vulcanization mold that has pores that are narrow in part and have a two-stepped part, and after vulcanizing a tire with this mold, the pores become narrow in the center, and Since the spout has a stepped part, the rubber that has flowed into the pores before vulcanization is cut, and the cut rubber is pulled out from both sides of the pores while remaining stuck to the vulcanized tire, resulting in fine rubber. No vulcanized rubber remains inside the holes, and gas can be smoothly vented during vulcanization even if the tire is vulcanized many times in succession.

Fruit” 1 example- Hereinafter, one embodiment of the present invention will be described based on the drawings.

In FIGS. 1 and 2, 1 is a core made of foamed gypsum or the like, and this core 1 has an annular shape.

It has the same shape as one of the two halves of the product tire at its equatorial plane. The outer peripheral surface 2 of the core 1 is formed with a large number of grooves 3 having substantially the same shape as the tread and shoulder surface of the product tire. A large number of pairs of recesses 6 and 7 are formed in the side walls 4 and 5 of the groove 3, which face each other. Each of the recesses 6, 7 has its radially outer end open to the outer circumferential surface 2.

These recesses 6 and 7 are formed by providing projections on the mold for forming the core 1, and by inverting these projections to form recesses 6 and 7.
7 may be formed, or may be formed by cutting off after forming the core 1. Reference numeral 8 denotes a thin metal member formed by gluing together the tips of tapered metal members extending in the direction connecting the pair of recesses 6 and 7 and being approximately parallel to the outer circular surface 2, but whose center line is slightly offset. It is a hole forming member. This pore forming member 8 is made of a material that will not be fused even if it comes into contact with molten metal, which will be described later, and is made of, for example, stainless steel. Both ends of this pore-forming member 8 have recesses 6 for each month,
After being inserted into the filling body 9 made of foamed plaster or the like,
10 is filled in the recesses 6 and 7, and from this, both ends of the pore forming member 8 are buried in the recesses 6 and 7, and the groove 3 is
Bridging as shown in the figure. Alternatively, the pore forming member 8
After embedding both ends of the pore-forming member 8 in the plaster blocks located between the recesses 6 and 7, inserting these plaster blocks into the recesses 6 and 7. It may be buried in. This pore-forming member 8 is preferably buried at a position where the distance S from the outer circumferential surface 2 of the core 1 is 2 mm or less. After the pore-forming member 8 is attached to the core 1, the core 1 is placed on the flat plate 11 so that its divided surface is in close contact with the flat plate 11. Next, the mold 12 is placed over the core 1, and the main mold 1 composed of the flat plate 11 and the mold 12 is then
3 surrounds the core l, and a hollow portion 14 is formed between the inner surface of the main mold 13 and the outer surface of the core 1. In this way, the hollow part 14
is formed, aluminum alloy,
Molten metal, such as a zinc alloy, is injected. At this time.

Even when the pore-forming member 8 comes into contact with molten metal, it does not fuse with the molten metal and maintains its shape. and.

When this molten metal cools and solidifies, a mold 15 is formed. At this time, the molten metal also flows into the three-dimensional space and solidifies, so a protruding bone portion 16 is formed on the inner surface of the mold 15 in a complementary relationship. The center portion of the forming member 8 is cast, and as a result, the m-hole forming member 8 is firmly held in the mold 15. Next, after removing the flat plate 11° formwork 12, the mold 15 and the core l are separated and the mold 15 is taken out. At this time, since the pore-forming member 8 is firmly held at its center by the bone part 16, it is transferred from the core l to the mold 15, and its both ends are pulled out from the filling body 9 and 10 and attached to the bone part. 16 protrudes from the outer surface as shown in FIG. Next, the pore forming member 8 protruding from the outer surface of the bone portion 16 is extracted from the bone portion 16. At this time, the II hole forming member 8 can be easily pulled out if lubricant is attached to the outer periphery. By this extraction, the bone part 16
There are many vent holes 17 that are almost parallel to the contour plane.
Each vent hole 17 is a through hole with both ends open, for example, the diameter is about 1.5 mm at both ends (exit) and about 1.0 mm near the center, and a stepped part is formed in the center.

Note that the diameter of the central portion is preferably 1.0 mm or less. The pore forming member 8 is shown in FIG. 4(A). The pore-forming member O8 is a tapered metal member 18, 19 (tip 20.
21 diameter 1.0mm, rear end 23.24 diameter 1°5
mm) parallel to each other, and its tip 20.21 is made of metal 3H.
The center lines of materials 18 and 19 are parallel to each other by 0.2 mmk.
Since the metal members 18 and 19 are simply glued together with a commercially available instant adhesive in a downwardly shifted state, the metal members 18 and 19 can be easily separated at the joint surface 22 by pulling outward from both ends of the vent hole 17. By doing so, the center part of the pore-forming member 8 can be made thinner than 1.0 mm in diameter, and a stepped part can be formed in the center part. It goes without saying that the cross sections of the metal members 18 and 19 may be polygonal. When a green tire is vulcanized using such a mold 15, gas and air generated during vulcanization flow into the vent hole 17 from both frontages.

Rubber from green tires also flows into the vent hole 17 from both openings. When the tire is taken out after vulcanization, since the vent hole 17 is stepped approximately in the center, the spill is cut at the center step 11 and exits from the vent hole 17 with the tire attached to the tire from both ends. No rubber remains in the vent hole. This stage is 0.
It is desirable that the thickness is 1 mm or more, preferably 0.15 mm or more. Note that the tapered metal members '18 and 19 are made of stainless steel and are not easily deformed, so even after use, they can be reprinted by gluing the tips 20° and 21 again.

In addition, also in the pond of the pore forming member 8 shown in FIG. 4(A),
Pore forming members shown in FIGS. 4(B), (C), and (D) may also be used. here.

In the case shown in FIG. 4(B), the tip 25 has a diameter of 0°6.
A metal member 27 having a circular cross section with a rear end 2G of 1.5 mm and a metal member 19 are joined with their tips aligned with the same center line. The one shown in FIG. 4(C) has a metal member similar to the metal member 18 with a diameter of 0.5 mm at the tip.
A metal member 29 having a 6 mm cylindrical protrusion 28 and a metal member 19 are joined with their tips aligned with the center line. What is shown in FIG. 4(D) is the metal member 18
Taper the tip of the tip and make the diameter of the tip 30 0.6 m.
m, and the ends of the metal member 31 and the metal member 19 are joined with their center lines aligned with each other.

As explained above, according to the present invention, after vulcanization, the rubber cut at the center of the pore is pulled out from both sides of the pore while remaining stuck to the vulcanized tire. Therefore, no vulcanized rubber remains inside the pores, and gas can be smoothly vented during vulcanization even if the tire is vulcanized many times in succession.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention. Fig. 2 is a perspective view showing a part of the core, Fig. 3 is a perspective view showing a part of the mold, Fig. 4(A) is a side view of the pore forming member, Fig. 4(B), ( C) and (D) are side views of another pore-forming member. 1... Core 2... Outer surface 3... Groove
4, 5...Side wall 6.7...Recess 8
...Pore forming member 13...Main mold 14...
・Hollow part 15...Mold 16...Bone part I7
...Pore (vent hole) Figure 1 Figure 3 Figure 2 Tomi 4-Exit. （＾］

Claims (2)

[Claims] (1) It has a bone part on the inner peripheral surface that corresponds to the tire tread and the groove on the shoulder surface, and a vent hole in this bone part that is almost parallel to the contour surface and has a stepped part at the converging part in the center in the longitudinal direction. A vulcanized mold for tires characterized by having (2) A step of preparing a core having grooves on the outer peripheral surface that have the same shape as the tread and shoulder surfaces of the product tire, and multiple pairs of recesses formed on the opposing side walls of the grooves, and two tapered grooves. Both ends of the pore-forming member, which has a stepped portion formed in the converging portion by joining the tips of the shaped members, are inserted and buried in each pair of recesses, and the grooves are bridged by the pore-forming member. a step of surrounding the core with a main mold to form a hollow portion between the inner surface of the main mold and the outer surface of the core;
a step of injecting and solidifying molten metal into the hollow portion to form a mold, and casting a central portion of the porous molded member into the bone portion of the mold solidified in the groove; and the core;
A vulcanizing mold for tires comprising the step of separating the mold from the main mold, and then extracting tapered members from both sides of the bone of the mold to form pores in the bone of the mold. Production method