JPH06226744A - Mold and method for molding tire having exhaust groove - Google Patents

Abstract

PURPOSE:To make the ridge of the tread surface and recessed part of a tire sharp by forming a bone member from a bone part composed of a rib and a through-hole part contoured by the bone part and constituting a mold having an exhaust groove of the profile molding roll fitted in the through-hole part and the inner peripheral surface of a second holder. CONSTITUTION:A cylindrical joining surface 5 is formed to the inner peripheral surface of a second holder 3 to which the joining surface 4 coming into contact with the inner peripheral surface 2 of a first holder 1 is formed. The joining surface 9 coming into contact with the joining surface 5 is formed and a bone part 12 consisting of a rib 10 having a tire recessed part formed to the inner periphery thereof and a lug 11 is formed and a through-hole part 13 is provided to the region surrounded by the bone part 12 to form a bone member 8. A profile molding roll 15 is fitted in the through-hole part 13. An exhaust groove 19 is provided to the boundary part of the bone member 8 of the joining surface 5 of the second holder 3 and the molding roll 15 to be allowed to communicate with the open air. The molding space formed by the bone member 8 and the molding roll 15 is filled with a tire material and, when a tread surface and a recessed part are molded, the boundary ridgeline of both of them is sharply formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire molding die for molding a tire for a vehicle and a method for manufacturing the tire, and particularly to air and generated gas blocked in the molding space outside the die. The present invention relates to a tire molding die having an exhaust groove with a minute gap that allows smooth exhaust, and a method for manufacturing the tire molding die.

[0002]

2. Description of the Related Art In general, a tire molding die for molding a vehicle tire is often of a split mold type as shown in FIG. In FIG. 8, reference numeral 31 is a tread portion, which is formed by combining a plurality of arc-shaped divided sector molds in an annular shape, and has an annular shoulder portion 32.
Are arranged above and below in the tread portion 31. A tread surface portion 33 corresponding to the outer shape of the tire to be molded and a bone portion 34 corresponding to the concave portion of the tire are provided on the inner surface of the tread portion 31.

Conventionally, the tire molding die as described above is
The tread portion 3 is manufactured by a manufacturing method such as a plaster molding method, a sand casting method, a ceramic casting method, a die casting method, another precision casting method, an engraving method, and an electric discharge machining method.
3 and the bone portion 34 are integrally formed, or the bone portion 34 is welded to the inner peripheral surface of the tread portion 33 in advance. Therefore, in order to improve the characteristics of the tire, it is necessary to update the entire mold every time the design formed by the tread portion 33 and the bone portion 34 is updated.

Further, at the time of tire molding, it is necessary to separately process the exhaust hole in order to discharge the air and the generated gas blocked in the molding space out of the mold. In addition, it was impossible to manufacture the coaxiality, the circularity, etc. between the constituent members with high accuracy of, for example, 0.1 mm or less. Further, in order to ensure accuracy, it is necessary to spend a great deal of man-hours and time for hand-finishing, which not only increases the manufacturing cost of the mold but also requires a long manufacturing period. was there.

In order to solve the above-mentioned drawbacks, the applicant has already applied a profile ring having an inner peripheral surface corresponding to the outer shape including at least the tread surface of the tire to be molded, and abutting on the inner peripheral surface of the profile ring. A net ring having a joint surface and at least a part of a rib and a lug for forming a recess of the tire to be molded is connected in a mesh shape, and the net ring is provided with an inner peripheral surface of the profile ring. Proposals have been made with the content of being placed on top (see Japanese Patent Publication No. 4-75121).

As another proposal, in a tire molding die of a split mold system having at least a plurality of divided tread portions, and a method for manufacturing the same, a plurality of tread portions of at least a tire to be formed are A profile portion having an inner peripheral surface formed of a curved surface corresponding to the tread surface,
And a net portion having a joint surface that abuts the inner peripheral surface of the profile portion and having ribs and / or lugs for forming the recess of the tire to be formed (special feature (See Japanese Patent Publication No. 4-75123).

FIG. 9 is a sectional view of an essential part showing another embodiment of the above proposal, and the same parts are designated by the same reference numerals as those in FIG.
In FIG. 9, the tread portion 31 includes a holder 35, a profile portion 36, and a net portion 37. The profile portion 36 is formed, for example, in a ring shape or an arc shape, and a curved tread surface portion 33 corresponding to the tread surface of the tire to be molded is formed on the inner circumference.

Next, the net portion 37 is also formed in a ring shape or an arc shape, a joint portion abutting the inner peripheral surface of the profile portion 36 is formed on the outer periphery thereof, and a concave portion of the tire to be formed is formed on the inner periphery thereof. The ribs and / or the lugs for forming the ribs 34 are respectively formed to correspond to the ribs and / or the lugs. The net portion 37 is joined to the profile portion 36 via a taper pin 38, for example, and the profile portion 36 is joined to the holder 35 via a fastening means such as a bolt (not shown) to form the tread portion 31.

[0009]

According to the above proposal, the ridgeline forming the boundary between the tread surface and the concave portion of the tire to be molded can be made sharp and clear, and the metal mold for high-precision tire molding can be obtained. It is possible to obtain the effect that can be manufactured at low cost and in a short period of time. However, there are some problems as described below. That is, since the profile portion 36 and the net portion 37 are joined to each other through the curved tread surface portion 33, the air or the generated gas blocked in the molding space is discharged from the gap between the profile portion 36 and the net portion 37. , Is discharged to the outside through the gap between the taper pin 38 and the hole and the gap between the holder 35 and the profile portion 36.

Therefore, the air or the generated gas is used as the tread portion 3
Since the rubber moves along No. 3, the raw material rubber for forming the tire is also filled along the tread portion 33, so that so-called burr may occur. This burr hardly occurs if the gap between the profile portion 36 and the net portion 37 is, for example, 0.03 mm or less, but a thin film-like burr is generated due to the above-mentioned gap gradually increasing after long-term use. Occur.

When the burr in the direction along the tread surface portion 33 is generated as described above, the burr protrudes into the recess of the molded tire, and the ridge line corresponding to the boundary between the tread surface and the recess portion becomes unclear or unclear. Will reduce the commercial value of. Therefore, the burr is manually removed, but the recess formed in the tire has a zigzag shape in the circumferential direction, and has a complicated shape depending on the design, so that the burr removal operation is complicated. In addition, there is a problem that it takes time and man-hours.

The present invention solves the problems existing in the above-mentioned prior art, has the features of the proposed improvement sufficiently, and has an exhaust groove in which manual removal of burrs after tire molding is unnecessary. An object is to provide a tire molding die and a method for manufacturing the same.

[0013]

In order to achieve the above object, in the first invention, a first holder forming an outer shell portion and a joint surface abutting on an inner peripheral surface of the first holder are provided. And a skeleton having ribs and / or lugs for forming a concave portion of a tire to be molded and having a joining surface that abuts an inner peripheral surface of the second holder, and the skeleton. A bone member having a penetrating portion outlined by the above, an inner peripheral surface corresponding to an outer shape including a tread surface of a tire fitted into the penetrating portion of the bone member, and at least the second portion.
The technical means of adopting a profile forming piece having an inner peripheral surface of the holder and a joint surface that comes into contact with the holder is adopted.

Next, in the second aspect of the present invention, the joining surface is processed on the inner circumference of the first holder forming the outer shell, and the outer circumference of the second holder is brought into contact with the joining surface of the first holder. The joining surface is processed and another joining surface is processed on the inner circumference, and the joining surface that abuts the joining surface formed on the inner circumference of the second holder is processed on the outer circumference, and at least the concave portion of the tire to be formed is formed. A rib having a rib and / or a lug for forming, and a bone ring having an inner periphery processed to produce a bone ring, and a region having a penetrating portion by processing a region outlined by the bone of the bone ring A member is manufactured, and a profile ring is manufactured in which a joint surface that comes into contact with the inner peripheral surface of the second holder is processed on the outer circumference and a curved surface is formed on the inner circumference to form at least a tread surface of a tire to be molded. , The profile to be molded from this profile ring The profile forming piece having an outer shape corresponding to the outer shape of the tread surface of the yarn is cut off, the bone member is joined in the second holder, and the profile forming piece is fitted to the through portion provided in the bone member, and these constituent members are formed. Was adopted in the first holder.

In the present invention, each of the first holder, the second holder and the bone member may have a ring shape, or a so-called split mold system having a radial dividing surface with respect to the axis of the tire to be molded. Alternatively, it may be a sector mold.

When the ring-shaped bone member is joined in the second holder formed in the ring shape, it is desirable that at least one of the holders is radially cut and joined to the axis of the tire to be molded. .

Further, the profile forming piece may be formed by the remaining material of the through portion at the time of manufacturing the bone member.

[0018]

With the above construction, the ridgeline forming the boundary between the tread surface and the recess of the tire to be molded can be made sharp and clear, and a highly accurate tire molding die can be obtained at low cost. Naturally, the effects that the improvement proposal has are exhibited, and the following actions can be expected.

That is, since the boundary surface between the bone member and the profile forming piece is formed in a direction substantially orthogonal to the tread surface of the tire to be molded, even if a burr is temporarily generated along this boundary surface. , The commercial value of molded tires cannot be reduced. On the other hand, even in the case of removing the above-mentioned burr, it can be performed easily and in a short time by a simple means of moving the cutter along the tread surface of the tire.

[0020]

FIG. 1 is an explanatory view showing an embodiment of the present invention,
(A) shows a cross section of a main part of a plane including an axis of a tire to be molded, and (b) shows a developed inner surface of a main part of a molding space. Note that, in FIG. 1, (a) corresponds to a cross section taken along the line AA in (b). FIG. 2 is a sectional view taken along the line BB of FIG. 1 (b). In FIGS. 1 and 2, CL is a center surface of a tire to be molded, and SL is a radial division surface centered on the axis of a ring-shaped molding die. That is, the molding die shown in FIG. 1 and FIG.
Fig. 123 shows an example of a split mold type tire molding die in which one set of a plurality of tread portions is formed from one block of tread ring, as described in Japanese Patent No. 123.

In FIGS. 1 and 2, reference numeral 1 is a first holder, which is formed in a ring shape and has an inner peripheral surface 2 formed as a right cylindrical surface to form an outer shell portion of a tire molding die. To do. Reference numeral 3 denotes a second holder, and a joint surface 4 that abuts the inner peripheral surface 2 of the first holder 1 is formed on the outer periphery of the second holder.
A curved cylindrical joint surface 5 and an abutting surface 7 that contacts the shoulder ring 6 are formed on the inner circumference.

Next, reference numeral 8 denotes a bone member, which is formed with a joint surface 9 that abuts on the joint surface 5 of the second holder 3 on the outer periphery and a concave portion of the tire to be molded on the inner periphery. A bone portion 12 including the rib 10 and / or the lug 11 is formed. Reference numeral 13 denotes a penetrating portion, which is an area surrounded by the bone portion 12, that is, a hexagonal area surrounded by the zigzag rib 10 in the expanded shape, or a polygonal area surrounded by the rib 10 and the lug 11. It is provided. In addition, 14 is a lug member, the rib 10,
It is provided to connect the ten.

Reference numeral 15 is a profile forming piece, which is formed to have an outer contour corresponding to the penetrating portion 13 of the bone member 8 and has an outer periphery which is in contact with the joint surface 5 of the second holder 3.
6 is formed, and the inner peripheral surface 17 corresponding to the outer shape including at least the tread surface of the tire to be molded is formed on the inner surface. The profile forming piece 15 is fitted into the penetrating portion 13 of the bone member 8. Reference numeral 18 is a mounting bolt, which is used to attach the bone member 8 and the profile forming piece 15 to the second holder 3
It is for fixing to the joint surface 5 of.

Next, reference numeral 19 is a ventilation groove, which is formed in the joint surface 5 of the second holder 3 facing the boundary between the bone member 8 and the profile forming piece 15 so as to communicate with the outside air. The surface roughness of the joint surface 5 of the second holder 3, the joint surfaces 9 and 16 of the skeleton member 8 and the profile forming piece 15 and the contact side surface of the skeleton member 8 and the profile forming piece 15 is 20 to 80 μm.
It is preferable to set m. By forming in this way, a ventilation gap is formed between the joint portions of the second holder 3, the bone member 8 and the profile forming piece 15, and serves as a flow path for closed air and / or generated gas during tire formation. An exhaust path to the outside is formed through the ventilation groove 19.

With the above configuration, the operation will be described next. First, the bone member 8 is mounted in the second holder 1 by the mounting bolt 1
Then, the profile forming piece 15 is fitted into the penetrating portion 13 provided in the bone member 8 and fixed through the mounting bolt 18. Next, the second holder 3 configured as described above
, A plurality of arc-shaped sector molds, which are configured by joining the above-mentioned in the first holder 1 via mounting bolts (not shown), are assembled in a ring shape through the dividing surface SL,
By fitting the shoulder ring 6 through the abutting surface 7, the tire molding die is constructed.

Next, when a ring-shaped tire material (not shown) having a substantially C-shaped cross section is inserted and internal pressure is applied, the tire material is formed by the bone member 8 and the profile forming piece 15. It is filled in the molding space, the tread and the recess are molded, and the vulcanization process holds the profile.

In this case, for example, as shown in FIG. 8, when the tread surface portion 33 and the bone portion 34 are simultaneously machined by electric discharge machining (so-called bottom machining in electric discharge machining) as shown in FIG. Because of this, the corners that form the boundary between the tread portion 33 and the bone portion 34 do not become sharp, and so-called "R" is attached. Therefore, in order to sharpen this corner, another electrode must be used and reworked.

However, in the present invention, as shown in FIG. 1, the bone member 8 is provided with the penetration portion 13, and the penetration portion 1 is provided.
Since the profile forming piece 15 is fitted in the groove 3, the boundary surface between the bone member 8 and the profile forming piece 15 can be formed substantially orthogonal and sharp. As a result, the boundary ridgeline between the tread surface of the tire to be molded and the recess can be sharply formed, and the commercial value can be improved.

Further, between the joint portions of the second holder 3, the skeleton member 8 and the profile forming piece 15, the ventilation gap or the exhaust groove of the minute gap is formed as a result as described above, and this exhaust groove is formed. Circulates to the outside through the ventilation groove 19. Therefore, the air and / or the generated gas, which is blocked in the molding space during tire molding, is easily discharged to the outside through the exhaust groove and the ventilation groove 19.
The profile of the tire to be molded can be secured.

Since the exhaust groove is a minute gap, the tire material does not enter the exhaust groove during tire molding, and undesired burrs do not occur on the surface of the tire to be molded. Further, even if burrs are generated, the burrs remain insignificant, and since the direction of burr formation is substantially perpendicular to the tread surface of the tire to be molded, the boundary ridgeline between the tread surface and the recess is made unclear or unclear. Does not reach. Further, even when the burr is removed by a cutter or the like, it can be performed by a simple means of moving the cutter or the like along the tread surface of the tire.

3 to 7 are a sectional view and a perspective view of a main portion for explaining the manufacturing process of the tire molding die in the embodiment of the present invention. First, in FIG.
Reference numeral a is a second holder material, which is integrally formed in a ring shape and has a straight cylindrical joint surface 4 on the outer circumference, a curved cylindrical joint surface 5 on the inner circumference, and the shoulder ring 6 shown in FIG. The abutting surfaces 7 that contact each other are processed. It should be noted that these machined surfaces are highly accurately finished using, for example, an NC lathe (the same applies to the following machining).

Next, in FIG. 4, reference numeral 8a denotes a bone ring, which is integrally formed in a ring shape and has a joint surface 9 which contacts the joint surface 5 shown in FIG. 3 on the outer circumference and the joint surface 9 shown in FIG. 1 on the inner circumference. Inner surfaces 10a, 11a and 14a corresponding to the surfaces of the ribs 10, the lugs 11 and the lug member 14 and the above-mentioned FIG.
The abutting surfaces 7 that come into contact with the shoulder ring 6 shown in FIG. The part indicated by the broken line is a part processed by, for example, electric discharge machining described later.

FIG. 5 is a cross-sectional view of an essential part showing a state after processing of the bone ring 8a shown in FIG. 4, and the same portions are denoted by the same reference numerals as those in FIG. In FIG. 5, reference numeral 13 is a penetrating portion, which is formed in a region surrounded by the bone portion 12. In this case, the penetrating portion 13 can be processed by, for example, wire cut electric discharge machining or laser machining. Next, the rounding of the tip portion 20 of the bone portion 12 and the side wall portion 13a of the penetrating portion 13 are finished by electrical discharge machining using, for example, an electrode formed in a corresponding contour, and the bone member shown in FIG. A ring-shaped bone ring 8a corresponding to 8 is formed.

The bone ring 8a is joined in the second holder material 3a as shown in FIG. 3 and FIG.
Although the joined body of the second holder 3 and the bone member 8 is formed as shown in Fig. 5, the outer diameter of the bone ring 8a is formed larger than the inner diameter of the end of the second holder material 3a. Therefore, the two cannot be joined together as a unit. For this reason, as shown in a perspective view in FIG. 6, a cut surface 21 along the plane including the axis is processed on the bone ring 8a as shown by a broken line.

That is, by providing the cut surface 21 on the bone ring 8a and applying an external pressure in a state where the cut surfaces 21 and 21 opposed to each other are mixed with each other, the outer diameter of the bone ring 8a is set to the second value shown in FIG. It is possible to make the inner diameter smaller than the inner diameter of the end portion of the holder material 3a, and it is possible to join the both as it is. The outer diameter of the bone ring 8a is formed to be slightly larger in accordance with the cutting allowance when the cutting surface 21 is formed, so that when the second ring is joined to the second holder material 3a, the second
Not only the joint surface 5 of the holder material 3a and the joint surface 9 of the bone ring 8a but also the cut surface 21 of the bone ring 8a can be brought into close contact with each other.

In the above description, the example in which the bone ring 8a has one cut surface 21 is shown, but a plurality of cut surfaces 21 may be provided. The bone ring 8a
The screw holes and bolt holes to be provided in the second holder material 3a may be formed before joining, or the screw holes may be formed as co-holes after joining. Further, as shown in FIG. 9, when the bone ring 8a and the second holder material 3a are fixed by the taper pin 38, it is preferable to form a pin hole after joining them.

In FIG. 7, reference numeral 15a is a profile ring, which is integrally formed in a ring shape and has a joint surface 16 which is in contact with the joint surface 5 shown in FIG. The curved surface 17 for forming the tread surface is processed. And this profile ring 1
A plurality of profile forming pieces 15 having an outer shape corresponding to the outer shape of the tread surface of the tire to be molded are cut out from 5a by, for example, wire cut electric discharge machining or laser machining. The profile forming piece 15 thus formed
Are fitted into corresponding penetrating portions 13 provided on the bone ring 8a, respectively, and are fixed to the second holder material 3a (see FIG. 3) via the mounting bolts 18 as shown in FIG.

As described above, the second holder material 3a
Since the composite component member in which the bone ring 8a and the profile forming piece 15 are joined is formed in the inside, this composite component member should be formed in the state of being joined in the first holder 1 (see FIG. 1). It is cut along a radial dividing surface with respect to the axis of the tire to form a so-called split mold or sector mold.

In this embodiment, an example in which the lug member 14 is provided between the ribs 10 is shown.
It is also applicable to the configuration lacking. Although the example in which the profile forming piece 15 is cut and formed from the profile ring 15a has been described, the profile forming piece 15 may be formed by using a cut block when the penetrating portion 13 is formed in the bone ring 8a shown in FIG. Further, although the case where the tire molding die is a split mold or a sector mold is described, for example, a ring-shaped mold which is divided into upper and lower parts on or near the center surface of the tire as described in Japanese Patent Publication No. 4-75121. Of course, it is also applicable to. In the case of manufacturing a split mold type molding die, at the time of joining the second holder material 3a and the bone part ring 8a, at least one of them may be provided with a cut surface along a plane including the axis.

[0040]

EFFECTS OF THE INVENTION Since the present invention has the structure and operation as described above, the following effects can be obtained. (1) Since the bone member and the profile forming piece are joined to the inner surface of the second holder, the boundary ridgeline between the tread surface of the tire and the recess can be sharply formed, and the manufacturing cost of the mold can be reduced. The production period can be shortened. (2) The joint surface and profile surface of the constituent members can be processed with high precision using, for example, an NC lathe, and
Since the ribs and lugs for forming the recesses of the tire can be positioned in a meshed state, the dimensional accuracy can be greatly improved. (3) Since a minute gap exists between the constituent members, an exhaust groove is formed as a result, which facilitates discharge of the closed air and the generated gas in the molding space. (4) Since the boundary surface between the bone member and the profile forming piece is formed in a direction substantially orthogonal to the tread surface of the tire to be molded, even if a burr is generated along this boundary surface, It does not reduce the commercial value of the molded tire. (5) Even when deburring work is performed, it can be performed easily and in a short time by a simple means of moving the cutter along the tread surface of the tire.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of the present invention, (a) is a cross-sectional view of a main part of a plane including an axis of a tire to be molded, (b)
Corresponds to the inner surface of the expanded main part of the molding space, and (a) corresponds to the section taken along the line AA in (b).

FIG. 2 is a sectional view taken along line BB of FIG. 1 (b).

FIG. 3 is a cross-sectional view of a main part for explaining a manufacturing process of a tire molding die according to the embodiment of the present invention.

FIG. 4 is a cross-sectional view of a main part for explaining a manufacturing process of a tire molding die according to the embodiment of the present invention.

FIG. 5 is a cross-sectional view of an essential part for explaining the manufacturing process of the tire molding die according to the embodiment of the present invention.

FIG. 6 is a perspective view of a main part for explaining a manufacturing process of a tire molding die according to the embodiment of the present invention.

FIG. 7 is a cross-sectional view of an essential part for explaining the manufacturing process of the tire molding die according to the embodiment of the present invention.

FIG. 8 is a partial cross-sectional side view showing an example of a conventional tire molding die.

FIG. 9 is a sectional view of an essential part showing an embodiment of the improvement proposal.

[Explanation of symbols]

 1 1st holder 3 2nd holder 8 Bone member 15 Profile forming piece

Claims (2)

[Claims] 1. A first holder forming an outer shell portion, a second holder having a joint surface that abuts on an inner peripheral surface of the first holder, and an inner peripheral surface of the second holder. A bone member having a joint surface to be in contact with and a rib portion and / or a lug for forming a recess of a tire to be molded, and a penetrating portion outlined by the rib portion, and a penetrating member of the bone member. And a profile forming piece having an inner peripheral surface corresponding to an outer shape including at least a tread surface of a tire to be molded and a joint surface abutting against the inner peripheral surface of the second holder. A mold for forming a tire having an exhaust groove to be formed. 2. A joint surface is formed on the inner circumference of a first holder forming an outer shell portion, and a joint surface is formed on the outer circumference of the second holder so as to abut against the joint surface of the first holder. And a rib for forming at least a concave portion of the tire to be molded, by processing another joint surface on the circumference, and a joint surface that contacts the joint surface formed on the inner circumference of the second holder is formed on the outer circumference. Alternatively, a bone ring in which a bone portion corresponding to a lug is processed on the inner circumference is manufactured, and a region outlined by the bone portion of the bone ring is processed to manufacture a bone member having a penetrating portion. 2. A profile ring having a joint surface that abuts the inner peripheral surface of the holder 2 is machined on the outer periphery and a curved surface is machined on the inner periphery to form the tread surface of the tire to be molded, and molded from this profile ring. Corresponds to the outer shape of the tire tread A profile forming piece having an outer shape is cut out, a bone member is joined in the second holder, the profile forming piece is fitted in a through portion provided in the bone member, and these constituent members are joined in the first holder. A method for manufacturing a tire-molding die having an exhaust groove.