JPS5947660B2 - Tire filler condition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a tire bead filler having a metal ring-shaped bead wire as a core by an injection molding method. This makes it more reliable and easier.

Conventionally, tire bead fillers have been manufactured by extruding filler material and then attaching bead wires to the filler material by methods such as gluing, clamping, and inserting.

In this case, manufacturing is very troublesome, requires a lot of manpower and time, and has the drawback of poor mass productivity.

In addition, there was also the problem that work efficiency and quality were greatly influenced by the skill of the worker, and that product variations were likely to occur.

On the other hand, if the injection molding method is used, in which the bead wire is inserted as an insert into the mold of an injection molding machine and the filler material is injected around it to form the bead filler, extrusion molding Even a bead filler with a more complicated shape can be easily molded than a bead filler, and the adhesion between the bead and the filler material is good, dimensional accuracy can be improved, and the manufacturing process can be automated and labor-saving easily.

As described above, the injection molding method provides many advantages, but on the other hand, the following problems arise.

That is, the bead filler needs to be molded as raw rubber (unleaded) in preparation for later tire molding (lead addition).

However, when rubber is injection molded without vulcanization,
A phenomenon occurs in which the rubber material sticks to the mold cavity surface.

This occurs because the green rubber sticks to metal parts such as the mold cavity surface because the rubber is not vulcanized, and as the surface temperature of the mold cavity surface increases, the green rubber becomes more likely to stick.

In addition, in the case of injection molding, especially nozzles, runners,
Since the temperature of the rubber material increases during its flow through the gate, the rubber material tends to stick to the mold cavity surface.

If the molded product sticks to the mold surface in this way, it becomes difficult to open the mold after molding is completed, and even after the mold is opened, it is still difficult to take out the molded product, and it is difficult to remove the molded product. This often results in deformation of the unvulcanized molded product.

The fact that it is difficult to take out the molded product and that the work takes time can be said to be a fatal drawback for the automation (mechanization, labor saving) of the entire molding process.

The present invention has been made in view of the above-mentioned problems, and it is possible to easily manufacture a raw rubber-like bead filler with a built-in or bonded metal ring-shaped bead by injection molding, and also to make it possible to easily manufacture a raw rubber-like bead filler with a built-in or bonded metal ring-shaped bead. By using it, it is easy to release the molded product, and it also prevents the molded product from losing its shape.
This makes it possible to obtain high quality molded products.

That is, in the present invention, when a tire bead filler is molded using an injection molding machine, a ring-shaped bead wire is loaded into a shell mold that can be opened and closed separately from the mold body of the injection molding machine, and then The shell mold is removably loaded into the mold body, and then molten rubber such as natural or synthetic rubber is injected and filled into the shell mold within the mold body. The rubber and bead wire are integrated to form a bead filler, and then,
The present invention is characterized in that the bead filler is taken out from the mold body through the shell mold, and further, the bead filler is taken out from the shell mold outside the mold body.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment using a horizontal rubber injection molding machine, and shows the mold in an open state.

In the figure, 1 is a fixed plate of the mold body in an injection molding machine, to which a fixed side mold plate 2 is attached, and 4 is a movable plate of the same mold body, to which a movable side mold plate 3 is attached.

The fixed platen 1 and the movable platen 4 are connected to each other so as to be openable and closable via a plurality of guide rods (not shown), and thereby the stationary mold platen 2 and the movable mold platen 3 are connected to each other so as to be freely openable and closable.

Reference numerals 21 and 31 designate mold cavity surfaces, which are recessed in opposing surfaces of the stationary side mold platen 2 and the movable side mold platen 3.
and 31 form a mold cavity 5 that can be freely opened and closed.

51 is a sprue, 52 is a runner, and 53 is a gate. A plurality of the runners 52 are provided in a radial arrangement, and their bases are communicated with the sprue 51, and their tips are connected to the mold cavity 5 through the gates 53. It is communicated with a predetermined portion of the holder, that is, a position that does not interfere with the holding fitting 6.7, which will be described later.

In addition, around the sprue 51 and the runner 52,
If necessary, in order to prevent the rubber material passing through the rubber material from being vulcanized and to improve the fluidity of the material, a circulation flow path (mainly a cooling medium such as cooling water) for temperature adjustment medium (mainly cooling medium such as cooling water)
96.7 is a bead holding metal fitting (not shown),
They are provided at multiple locations in the mold cavity 5 so as to be movable forward and backward.

That is, the holding fittings 6 and 7 are provided at three or more locations in the circumferential direction of the mold cavity 5 so as to face each other. The other holding fitting 7 is slidably inserted into the hole 60.
These holding fittings 6 and 7 are slidably inserted into a guide hole 70 provided in the movable mold board 3, and each of these holding fittings 6 and 7 is
They are connected to the tips of piston rods 62 and 72 of hydraulic cylinders 63 and 73, respectively, and are configured to be able to move forward and backward into the mold cavity 5.

Reference numeral 8.9 is a shell mold, which is formed into a donut shape separately from the mold body, and is configured to be split in the axial direction, and when both shell molds 8 and 9 are closed, A mold cavity 80 having a shape corresponding to the shape of the bead filler to be molded is formed by these inner surfaces 81 and 91.

Further, one shell mold 8 is provided with a hole 82 for allowing insertion of the holding fitting 6 and a hole 83 communicating with the gate 53, and the other gel mold 9 is provided with a hole 83 for allowing insertion of the holding fitting 7. Hole 92 is provided 9 Next, to injection mold a bead filler using the above-mentioned apparatus, first, with the mold open as shown in FIG. The bead wire A is loaded, the shell molds 8 and 9 are closed and fixed by appropriate means, and the closed shell molds 8 and 9 are
After loading into the mold cavity 5, the mold is clamped.

At this time, each holding metal fitting 6 of the mold body, i.e. the mold plate 2゜3,
, 7 are retracted to a position where their tip surfaces 61 and 71 are flush with the mold cavity surfaces 21 and 31 as shown in FIGS. 1 and 2 so as not to interfere with the loading of the shell molds 8 and 9. I'll keep it.

When the shell molds 8 and 9 are loaded into the mold cavity, the holes 82 and 92 of the shell molds 8 and 9 correspond to the holding fittings 6 and 7, and the hole 83 communicates with the gate 53. They are fixed in their respective positions.

In this state, the bead wire A loaded in the shell molds 8 and 9 is in a free state without specifying the position thereof. After loading between plates 2 and 3, each hydraulic cylinder 6
3° 73 to enter the respective holding fittings 6, 7 into the shell molds 8, 9 through the holes 82, 92, and the tip surfaces 61.7
1. Clamp the internal bead wire A.

As a result, the bead wire A is centered at a predetermined position within the shell molds 8 and 9, and is partially clamped and fixed at the same number of locations around its circumference.

In this state, when molten rubber B such as natural or synthetic rubber is injected into the mold from the nozzle of an injection molding machine outside the area, this molten rubber B is transferred from the sprue 51 to the radial runner 52 and gate 53, and then to the shell mold 8. The mold hole 80 formed inside the cavity, that is, inside the shell molds 8 and 9, passes through the hole 83.
The bead wire A is injected into the bead wire A so as to surround the portions of the bead wire A other than those held by the holding fittings 6 and 7.

Then, after checking the filling by detecting the pressure inside the mold,
The hydraulic cylinders 63 and 73 are operated to retract each of the holding fittings 6 and 7 to a position where their tip surfaces 61 and 71 are flush with the inner surfaces 81 and 91 of the shell molds 8 and 9, as shown in FIG. let

Then, by moving the plunger or screw of the injection molding machine (not shown) forward again by a predetermined stroke and applying injection holding pressure, the molten rubber B is supplementally filled into the retreated traces of the holding fittings 6 and 7. .

In such a case, a temperature regulating medium such as cooling water is supplied into the mold body through a flow path (not shown), and the sprue 51° runner 5
2 and shell molds 8 and 9 in the mold cavity
The temperature of the rubber material inside is adjusted so as not to impair its fluidity and to prevent vulcanization from proceeding, so that the above-mentioned molding is performed in raw rubber, that is, in an unvulcanized or semi-vulcanized state.

As a result, during the initial injection and the second injection, the rubber material in the mold flows efficiently, filling every corner of the shell molds 8 and 9, and supplementary filling is also performed smoothly. Therefore, the bead wire A is completely surrounded by raw rubber in the shell molds 8 and 9,
A bead filler having a predetermined shape and incorporating the bead wire A in a predetermined portion is molded.

After that, each holding fitting 6, 7 is inserted into the hole 82 of the shell mold 8, 9.
．． 92 and return to its original position, that is, its tip surface 61.
71 is retracted to a position where it is flush with the mold cavity surface 21.31, and the mold body, that is, the fixed side mold platen 2 and the movable side mold platen 3 are opened, and the shell mold containing the bead filler is removed. 8°9 is taken out from the mold body via an ejector turbine (not shown).

At this time, although the molded product is in the form of raw rubber, it is not in direct contact with the cavity surface 21.31 of the mold body, so it can be taken out extremely easily and reliably through the shell molds 8, 9.

Incidentally, the actual separation and removal of the molded bead filler from the shell molds 8, 9 can be easily carried out by opening the shell molds 8, 9 outside the mold body.

In such a case, in order to facilitate and quickly separate and take out, the inner surface of the shell mold should be made of a material that has poor adhesion to raw rubber, such as cast iron or steel, but the inner surface is coated with Teflon, etc. It is desirable to use

Furthermore, when releasing and taking out the molded bead filler from the shell mold, it is effective to extremely cool the shell mold. It is not particularly limited,
Therefore, a detailed explanation thereof will be omitted.

The present invention is not limited to the above embodiments, but can also be implemented as follows.

That is, the bead wire A is not limited to a circular cross section, but may also be a square bead or a hexagonal bead.

Further, the shape and dimensions of the shell mold, and the positioning and holding means of the bead wire within the shell mold can be arbitrarily set according to the shape and dimensions of the bead and other requirements.

Moreover, as shown in FIG. 5, without using bead holding fittings,
Alternatively, the bead wire A' may be simply inserted into the shell molds 8', 9' and then loaded into the mold cavity for injection molding.

In this case, the bead wire N is placed biased toward the inner periphery in the shell mold, and the raw rubber is adhered to the outer periphery of the bead wire N, but even in this case, the adhesiveness between the bead wire N and the raw rubber serving as the filler material is good. Therefore, it is possible to obtain a product with sufficient strength.

Moreover, it is possible to reliably and easily take out the mold body from the mold body via the shell mold.

Although the illustrated example shows a mold for a horizontal injection molding machine, it goes without saying that a mold for a vertical injection molding machine may also be used in carrying out the present invention.

As explained above, according to the present invention, since the bead filler is molded by injection molding, it is easier to mold even a bead filler with a complicated shape than a bead filler made by extrusion molding.
In addition, the adhesion between the bead and the filler material is good, and dimensional accuracy can be improved.

Also, since raw rubber is molded as it is, the molded product can be used for later tire molding without any problems.

In particular, by loading the bead wire into a shell mold and then loading this shell mold into the cavity of the mold body, the mold is made into a so-called double structure for injection molding, so raw rubber can be used as it is. Even during molding, the raw rubber does not stick to the cavity surface of the mold body, and the molded product can be easily and smoothly taken out from the mold body through the shell mold. Because it protects the mold, it is possible to push it onto a conveyor using an ejector turbine when removing it from the mold body, making it easier to automate the removal of molded products and save labor, greatly improving mass production. There are also advantages.

[Brief explanation of drawings]

The drawings show an example in which a horizontal rubber injection molding machine is used. Figure 1 is a partially sectional front view showing the mold in an open state, and Figure 2 shows a shell mold with bead wire inside. FIG. 3 is an enlarged cross-sectional view of the main part showing the state loaded into the mold cavity, FIG. 3 is an enlarged sectional view of the main part showing the first injection state, and FIG. 4 is the main part showing the second injection state. FIG. 5 is a partially sectional front view showing the state of taking out the molded product.
FIG. 6 is an enlarged sectional view of essential parts showing an embodiment in which no holding fittings are used. 1... Fixed plate of the mold body, 2... Fixed side mold plate, 3
...Movable side mold plate, 4...Movable plate, 5...Mold cavity, 6, 7...Bead holding fitting, 8, 9...
・Shell mold, 21.31...Mold cavity surface, 8
0...Mold hole, A...Bead wire, B...Rubber material.

Claims (1)

[Claims] 1. When molding bead filler for tires using an injection molding machine, a ring-shaped bead wire is loaded into a shell mold that can be opened and closed separately from the mold body of the injection molding machine, and then the shell mold is removably loaded into the mold body,
Next, molten rubber such as natural or synthetic rubber is injected and filled into the shell mold within this mold body to integrate the rubber and bead wire within the shell mold to form a bead filler. Molding of a bead filler for a tire, characterized in that the bead filler is taken out from the mold body through a shell mold, and further the bead filler is taken out from the shell mold outside the mold body. Method.