JPS6026651B2 - Manufacturing method of split mold type tire molding mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a split-mold type tire molding die, particularly for forming a plurality of tread parts constituting a split-mold type tire molding die. A split mold type tire molding die in which a tread ring is cut using a cutting device using a wire as a cutting tool to form a set of multiple tread parts from one tread ring. This relates to a manufacturing method.

In general, tire molding molds are based on the so-called split molding method, which consists of a tread section and a shoulder section, which are annular combinations of a plurality of separate blocks formed in an arc shape. Often a type. The above-mentioned separate block is made by cutting the IJ ring in the ○ direction from a tread ring formed on the inner circumferential surface of the ring in a shape corresponding to the tread portion of the tire to be molded. Next, a conventional method for manufacturing the above-mentioned separate blocks will be explained with reference to FIG. FIG. 1A shows a plan view of the tread portion 1 of the tire molding die. The embodiment in FIG. 1A is composed of five separate blocks 1-1 to 1-5, where 2 in the figure is the tread surface, D is the diameter of the tread portion 1, and 1 is the separate blocks 1-1 to 1-5. It represents the arc length of each of 1-5.
Now, in order to obtain the five separate blocks 1-1 to 1-5 as shown in FIG. 1A, the tread section 1 shown in FIG. Assume that the illustrated tread ring 3 is to be cut. The cut portion 4 resulting from this cutting is the hatched portion in the figure. If the cutting distance of the cutting part 4 is d, the arc length 1' of the separate flock 1'--1'-5 obtained by the above cutting is (1
1d). Therefore, the separate flock 1'-1
It is not possible to obtain the desired tread portion as shown in FIG. 1A even if the footings 1'-5 are joined together in a ring. That is, separate flock 1'-1 with arc length 1' and 1'-5.
Even if they are combined in an annular shape, the length of the circumference will be insufficient and it will not be possible to obtain a mold having the above-mentioned diameter D. In consideration of this point, it is assumed that the arc length 1' of each separate flock 1'-1 to 1'-5 shown in FIG. 1B is equal to 1 shown in FIG. 1A. In this state, the above-mentioned diameter D is made larger by that amount, and separate blocks with a circular arc length of 1'=1, cut with a cutting distance d, are assembled in a ring shape as shown in FIG. 1B. do. However, even in this case, it is not possible to obtain a substantially perfect circular shape. This is because the cutting distance d is determined by the thickness of the cutting tool of the cutting machine, for example, since the cutting is performed by a cutting machine, and the cutting distance d of the cutting section 4 shown in FIG.
The width d on the inner protrusion side and the width d on the outer protrusion side are equal.
For this purpose, as mentioned above, if the tread as shown in FIG.
Even if the ring 3 is made large in consideration of the above-mentioned cutting allowance, each separate is cut as shown in FIG. 1B. This is because if the blocks 1'-1 and 1'-5 are combined, the shape becomes close to a pentagon with each side having a slight bulge on the outside. This undesirable condition can be caused by cutting bands with large cutting allowances as in the conventional case.
When cutting with a cutting machine such as a saw, the cutting section 4
The cutting allowance d of the cutting portion 4 becomes relatively large, and the cutting allowance d of the cutting portion 4 becomes relatively large.
The larger the value, the worse it becomes. Therefore, as shown in Figure 1C,
Prepare two tread rings 3-1 and 3-2,
There is no other choice but to cut it and take out, for example, separate blocks 1-1 and 1-5 having an arc length of 1 as shown in the figure. Therefore, in the conventional manufacturing method of the tread portion as shown in FIG. 1C, two tread rings are required to obtain one set of separate blocks, which not only increases the manufacturing cost,
There were drawbacks such as the need for high precision in determining the cutting position during cutting. SUMMARY OF THE INVENTION The present invention aims to solve the above-mentioned drawbacks, and in manufacturing a tread portion consisting of a plurality of separate blocks in a split-mold type tire molding die, a wire is used as a cutting tool. By cutting the tread rings using cutting equipment, it is possible to manufacture a set of tread parts from one tread ring, and the cutting position does not necessarily require high precision. First, it is an object of the present invention to provide a method for manufacturing a tire molding die using a split mold method, which enables the manufacturing cost to be reduced.

This will be explained below with reference to the drawings. 2 to 5 are diagrams for explaining the manufacturing method of the present invention, in which FIG. 2 is a partial cross-sectional view of one embodiment of a split mold type tire molding die, and FIG. Figure 2 is a side development view of the tread portion 1 along arrow A-A' (the above Figure 2 shows a sectional view taken along arrow B in Figure 3), Figure 4 is a plan view of the tread ring, and Figure 4 is a plan view of the tread ring. Figure 5 shows the double-dashed chain line C shown in Figure 4.
An enlarged view of the area surrounded by is shown.

Reference numerals 1, 2, 4 and d in the figure correspond to those in FIG. 5, 5' are shoulder parts, 6, 6' are contact surfaces between the tread part 1 and shoulder parts 5, 5', 7 is a contour surface, 8 to 10' are protrusions, 11 is a through hole, 12, 13 indicates the cutting part, 14 indicates the tread ring, and ○ indicates the tread ring 1.
4 (hereinafter referred to as diameter).

As stated at the beginning of this specification, a split mold type tire molding die is generally divided into a tread portion 1 and shoulder portions 5, 6' as shown in FIG. The portions 5, 5' are assembled together at the abutting surfaces 6, 6'.

Furthermore, the tread surface 2 has a shape corresponding to the shape of the tread portion of the tire to be molded, that is, the tread surface 2 has a contour surface 7, no protrusions 8, and 10 as shown in the embodiment shown in FIGS. 2 and 3. The tread portion 1 having a tread portion 1 is divided into a plurality of separate flocks as shown in FIG. 1A, for example. A fourth method for manufacturing a tread portion comprising a plurality of separate flocks constituting a tire molding die of the present invention
As shown in FIG. The manufacturing method of the present invention includes:
The tread portion 1 is constructed by cutting the tread ring 14 shown in FIG. 4, which is an annular body with a desired tread surface 2 formed on the inner circumferential surface, in the centripetal direction and dividing the blocks into separate blocks, which are arranged in a circular shape. It is. In the embodiment shown in FIG. 4, an embodiment in which the tread portion 1 is divided into nine parts is shown. Assuming that the diameter (strictly speaking, the diameter of the contour surface 7, hereinafter simply referred to as the diameter) is D (as shown in FIG. 2), the diameter 〇 of the tread ring 14 in the present invention is as follows.

It is manufactured in advance so that =D+4.

The tread ring 14 whose diameter is D' expressed by the above formula is cut at n cutting portions 4 with a cutting distance d as shown in FIG.
The tread portion 1 is constructed by roughly fitting the flocks together in a ring shape.
The diameter of the configured tread portion 1 is D. In addition, in FIG. 4, there are cutting parts 12 and 1 in addition to the cutting part 4.
3 is shown in the figure, the cutting portions 12 and 13 are for explaining another embodiment of the present invention to be described later, and are unrelated to the above embodiment. Therefore, in the description of the above embodiment, only the cutting portion 4 is focused. As stated at the beginning of this specification, when a set of tread parts are taken out from one block of tread rings, the true circular state of the combined tread parts may vary depending on the size of the cutting allowance d at the time of cutting. There is a problem of loss.

However, according to experiments conducted by the inventors of the present application, if the tread ring 14 is cut using a cutting device using a wire as a cutting tool, such as a wire electrode electrical discharge machining device, the cutting allowance d of the cutting portion 4 is 0. .3 willow or less, and a tire molded using a tire mold made of a tread portion cut and manufactured by the wire electrode electrical discharge machining apparatus described above can be made into a perfect circle shape as described above. Also about 0
．． It was found that the error was within the error range of the 03 side, causing no practical problems. Therefore, as shown in FIG. 4, the method for manufacturing a tire molding die of the present invention involves cutting the tread ring 14 in a cutting section 4 using a cutting device using a wire as a cutting tool.
For example, by using a wire electrode electrical discharge machining device), the cutting distance d is made as small as possible. In the above-mentioned cutting, as shown in FIG. 4, the cut surface of the cut portion 4 is cut so as to substantially intersect the center of the circle of the tread ring 14. That is, the center of the circle is placed on the extension of the line segment shown as the cutting section 4 in the case shown in FIG. Actually, the tread ring 14 shown in FIG. 4 is a three-dimensional object, and it is correct to explain it using a cut surface as described above. In this specification, the cutting direction is described as cutting in the centripetal direction. When the cut surfaces at the cut section 4 are joined together to obtain one tire molding mold as shown in FIG. When joining two tread parts, a difference in dimensions occurs on the joining surfaces, making it impossible to join them correctly. In addition, if there is a possibility that the tread ring 14 has internal stress, when the tread ring 14 is cut and separated by one of the cutting parts 4 shown in FIG. For example, a phenomenon occurs in which the closed portion of the portion 4 expands. Then, due to the Sekiguchi phenomenon of the cutting section 4, an undesirable situation occurs in which it becomes difficult to set the cutting positions of the other cutting sections 4. Another embodiment of the manufacturing method of the present invention for preventing this undesired state will be described. That is, first, in FIGS. 2 and 3, one of the abutting surfaces 6 and 6' (the abutting surface 6 in the embodiment shown in FIGS. 2 and 3) of the tread ring 14 A through hole 11 (see FIG. 3) reaching the outer circumferential surface of the tread ring 14 is formed in the tread ring 14. The through hole 11 is provided for each desired cutting section. Next, a wire of a cutting device, for example, a wire electrode of a line electrode electrical discharge machining device, is passed through the wire, and then the wire electrode is used to cross the tread surface 2 from each of the through holes 11 to other abutments as shown in FIG. A slit cut is made that reaches at least the surface 6'. The tread ring 14 is cut by the slit cutting.
Slit cutting portions 12 are formed at a plurality of locations across the tread surface 2, and while the slit cutting portions 12 are being cut, the tread ring 14 is Since the parts other than the tread ring 14 are integrally connected, even if internal stress is applied to the tread ring 14, the tread ring 14 will not be distorted. As described above, after cutting slits at a plurality of desired locations, cutting is performed from the outer circumferential surface of the tread ring 14 to both ends of the slit cut portion 12 using an appropriate cutting means (the cut portions resulting from the cutting process are (indicated by the cut 13 in FIGS. 3 to 5)
By doing this, it is possible to manufacture a tread portion divided into a desired plurality of pieces. Note that the cutting section 13
Even if the cutting allowance becomes large, it will not affect the tread surface 2. Furthermore, although it has been explained that the through hole 11 is provided in the abutting surface 6 or 6', the wire is passed through a gas vent hole (not shown) previously formed in the tread surface 2, and is passed across the tread surface 2 to the abutting surface 6. and 6
It is also possible to perform slit cutting that reaches at least both of . That is, in this case, the through hole 11 does not need to be formed. As explained above, according to the present invention, when manufacturing a plurality of divided tread parts in a split-mold type tire molding die, a cutting device using a wire as a cutting tool is used to cut the tread. By cutting the ring, it is possible to manufacture a set of tread parts from one tread ring, and there is no need to increase the precision of the cutting position when cutting, so the manufacturing process is simplified. It is possible to provide a method for manufacturing a tire molding die using a split mold method, which not only achieves high performance but also reduces manufacturing costs.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining one embodiment of a method for manufacturing a tread portion in a conventional split mold type tire molding die, and FIGS. 2 to 5 are diagrams for explaining the manufacturing method of the present invention. 2 is a partial sectional view of one embodiment of a split mold type tire molding die, FIG. 3 is a side development view of the tread section taken along arrow A-A' in FIG. 2, and FIG. Figure 5 is a plan view showing how to divide the treaded ring.
The figures each show an enlarged view of the area indicated by arrow C in FIG. 4. Symbols in the figure: 1 is the tread portion, 2 is the tread surface, 3 is the tread ring, 4, 12 and 13 are the cutting portions, 5 and 5' are the shoulder portions, 6 is the abutment surface, 7 is the contact surface,
8 to 10 represent protrusions, 11 represents a through hole, and 14 represents a tread ring. Figure 1 Figure 5 Figure 2 Figure 4 Figure 3

Claims (1)

[Scope of Claims] 1. A method for manufacturing a tire molding die using a split mold method, which is formed by dividing a tread ring into a plurality of tread parts and a shoulder part, in which a single tread ring is divided into a plurality of tread parts and a shoulder part. The tread ring is divided into tread parts, and the divided tread parts are combined to form a tire molding mold, and when dividing the tread ring,
cutting the single tread ring using a cutting device in a centripetal direction such that the cut surface substantially intersects the center of the tread ring to form a plurality of tread portions; A plurality of tread parts are combined in an annular shape so that their corresponding cut surfaces are joined to form the tire molding mold, and the tread ring is divided to form a plurality of tread parts. When the number of divisions is n, the desired diameter of the tire mold is D, and the cutting allowance when cutting the tread ring by the cutting device is d, the tread ring before cutting is: A method for manufacturing a split mold type tire molding die, characterized in that the ring is formed to have a diameter of (D+nd/π). 2. Cutting by the cutting device is performed by creating one or more through holes extending from one surface of the tread ring to the other surface of the tread ring, and cutting from each of the plurality of through holes. The slit is cut until it reaches at least the abutting surface of the tread ring against the shoulder portion, and after the cutting process, the slit is cut between the ends of the plurality of slits and the outer peripheral surface of the tread ring. A method of manufacturing a split mold type tire molding die according to claim 1, wherein the tread ring is divided into a plurality of tread parts.